Rabbi Abraham Eben Ezra,
Raaba (1089-1164)
Rabbi Abraham Eben Ezra, Raaba: one of the great sages of Spain; spent his entire life wandering. He composed dozens of essays on different subjects: Poetry, grammar, commentary, astrology, etc.. Among his books are Yesod Mora [The Foundation of Fear] HaMispar [The Number], HaIbur [Conception], Safa Brurah [Clear Language], HaTe’amim [The Taamim], Reishit Hochmah [The Beginning of Wisdom].
Rabbi Abraham Ben Mordechai Azulai
(1570-1644)
Rabbi Abraham Ben Mordechai Azulai: A Kabbalist Rabbi from Fez, Morocco, whose family was banished from Spain in 1492. He immigrated to Israel in 1615 and died in Hebron. Rabbi Haim David Yosef Azulai, HaHida, who was one of his descendants, wrote words of praise about him. Rabbi Abraham Azulai composed several Kabbalah books, including Ohr HaChama [Light of the Sun], Hesed L’Avraham [Mercy unto Abraham], Zoharei Hama [Radiance of the Sun]—an abridged version of Rabbi Abraham Glanati’s Commentary to the Zohar, Baalei Brit Avraham [Abraham’s Allies].
Rav Abraham Isaac HaCohen Kook,
HaRaiah Kook (1865-1935)
Rabbi Abraham Isaac HaCohen Kook was among the greatest sages of Israel in the last one hundred years. For many, the image of the Rav Kook symbolized the transition from the exile to The Land of Israel. He was Chief Rabbi of “Boysk Yeshiva,” and in 1904 moved from “Volozhin Yeshiva” to Jerusalem, where he served as the first Chief Ashkenazi Rabbi in The Land of Israel.
The Rav Kook had a great impact on the Jewish education in Israel, attempting to unite the different factions and reviving the approach to the research and study of Judaism. The Rav Kook supported the study of the wisdom of the hidden and was one of Rav Yehuda Ashlag’s (Baal HaSulam) friends.
His teachings are extensively detailed in many books, such as: Orot HaKodesh [Lights of Sancitty] vols. 1, 2, 3, Letters vols. 1, 2, 3, Essays of the Raiah, Orot [Lights], Orot HaTorah [Lights of the Torah], Orot Hateshuva [Lights of Repentance], and numerous others.
The Gaon [great scholar] Rabbi Elijah,
GRA, The Vilna Gaon (1720-1797)
The Vilna Gaon, GRA, lived his entire life in Vilna. He was one of the greatest sages and was extremely knowledgeable in general, particularly in sciences. The Vilna Gaon composed more than seventy books interpreting The Bible, which excelled in their simplicity and clarity. GRA became known as the greatest opposer to the Hassidut movement. He wished to move to The Land of Israel and even began his journey there. However, due to hardships on the way, he returned to Vilna. A group of his disciples carried out his instruction and founded the congregation of the Prushim [seclusive].
Rabbi Baruch Ben Abraham of Kosov
(…-1792)
Rabbi Baruch Ben Avraham of Kosov, a Kabbalist from the sages of Poland, from the first generation of the Hassidut, a student of Rabbi Menahem Mendel of Vitebsk and the Maggid [Sayer] of Mezeritch. He composed two Kabbalah books: Pillar of the Work and Foundation of the Faith, commentaries on the Torah.
Rav Baruch Shalom Ashlag,
Rabash (1907-1991)
Rav Baruch Shalom Ashlag (Rabash) was the eldest son and follower of Rav Yehuda Leib HaLevi Ashlag (Baal HaSulam). From the young age of nine, he began to study with his father, joining him on his trips to the Rabbi of Porsov and the Rabbi of Belz.
In 1921, Rabash immigrated to Israel along with his father, and at the age of twenty, he was ordained to the Rabbinate by the High Court of Justice of the ultra-orthodox congregation and the Chief Rabbi of Jerusalem, Rabbi Chaim Zonenfeld, Rabbi Yaakov Moshe Harlap, and Rav Raiah Kook. By so doing, he received, in compliance with his father’s demand, ordainment from both the ultra-orthodox and the Zionist movement.
Rabash studied Kabbalah with his father for many years and began teaching at his father’s request. Following the demise of Baal HaSulam, Rabash became the leader of the congregation, at his students’ request. Rabash dedicated his life to disseminating the unique path of Baal HaSulam and to expanding the interpretation and explanation of his method.
Prior to his death, Rabash gave his student and follower, Rav Michael Laitman, a notebook within which he had documented his father’s words as he had heard them. Those notes have been published in the book Shamati [I Heard]. The group Bnei Baruch [Sons of Baruch], which was founded by Rav Michael Laitman for the purpose of disseminating his path, is named after Rav Baruch Shalom Ashlag.
Rabbi Chaim Ben Yitzhak of Volozhin
(1749-1821)
Rabbi Chaim Ben Yitzhak of Volozhin was one of the great Kabbalists, the students of the Vilna Gaon (GRA). He founded the great Yeshiva of Volozhin under GRA’s instruction. His books: Nefesh HaChaim [Soul of Life] discusses morals, Ruach Chaim [Spirit of Life] interprets Pirkei Avot [Ethics of the Fathers].
Rabbi Chaim David Yosef Azulai,
“HaChida” (1724-1806)
Rabbi Chaim David Yosef Azulai (HaChida) was born in Jerusalem and died in Livorno. He was a Halachah [religious law] adjudicator and a Kabbalist, a historian and a bibliographer. HaChida journeyed most of his life and was one of the first Hebrew bibliographers.
HaChida served as a Rabbi in Egypt for five years and visited Turkey, Greece, Italy, France, England, and Germany, among others. Wherever he traveled, he researched and searched for ancient scripts, from which he copied important details, writing them in a diary called Good Circle. HaChida composed numerous books, including Holding the Blessing, Joseph’s Blessings, Sought Life, and The Courage of Joseph.
Rav Chaim Vital
(1543-1620)
Rav Chaim Vital, one of the great Kabbalists in Safed, the personal disciple and the sole follower of Rabbi Yitzhak Luria, The Ari.
Chaim Vital was born in Safed and died in Damascus. He was the student of Rabbi Moshe Alshich and Rabbi Moshe Cordovero (Ramak). In 1570, upon the Ari’s arrival in Safed, Rabbi Chaim Vital recognized his greatness and the uniqueness of his method and became his personal student. For a year and a half, he meticulously documented the words and customs of the Ari.
Prior to his passing in 1572, the Ari instructed all of his students to forget what he had taught them, except Chaim Vital. He specifically indicated that Chaim Vital was the only one allowed to continue to study his special method. In 1594, he moved to Damascus and lived there for the rest of his life. His writings were hidden and buried by his side as he had instructed. However, they were later removed from the grave and were published by members of his family.
His famous book The Tree of Life, describes the method of the Ari. Among other published writings are Eight Gates to the Ari, within which are “Gates of Reincarnation,” “Gate of Intentions,” “Gate of Introductions.” Additional published writings include The Book of the Treasures of Life, Four Hundred Silver Shekels, and Book of Visions.
Rabbi Yehuda Ashlag,
Baal HaSulam (1884-1954)
Rav Yehuda Ashlag, known as Baal HaSulam for his authoritative Sulam [Ladder] commentary on The Book of Zohar, as it served as a ladder to rise to complete goodness. Baal HaSulam was born in Poland and was educated by the Rabbi of Kloshin and the Rabbi of Porsov. He served as an adjudicator in Warsaw and immigrated to Israel in 1921, where he served as the rabbi of Givat Shaul and engaged in the study, interpretation, and dissemination of the wisdom of Kabbalah his entire life.
Baal HaSulam developed a new method of studying Kabbalah, allowing all those interested in reaching spiritual attainment to use it. In addition to composing the Sulam commentary on The Zohar, he explained and interpreted the writings of the Ari in his book, The Study of the Ten Sefirot.
In 1933, he published the book Matan Torah [The Giving of the Torah], in which he compiled articles on the topic of Kabbalah which he published in a newspaper. Baal HaSulam composed a series of introductions preparing the student for proper study of texts of Kabbalah and explaining the way of study. Among his compositions are “Introduction to The Book of Zohar,” “Introduction to The Study of the Ten Sefirot,” Panim Meirot ve Masbirot [a commentary on The Tree of Life], Or HaBahir [Bright Light], Beit Shaar HaKavanot [Gatehouse of Intentions], Pri Hacham [A Sage’s Fruit].
Rabbi Yosef Eliezer Rosenfeld
(…-1915)
Rabbi Yosef Eliezer Rosenfeld, a sage from Poland, was appointed as the Rabbi of Preishtetl in 1890. He composed the books Chavat Yair [Havot Yair] and Ateret Tzvi [A Crown of Glory].
Rabbi Yaacov Tzemach
Rav Yaacov Tzemach, a Kabbalist, a student of Rav Shmuel Vital, son of Rav Chaim Vital. Rav Yaacov Tzemach was born in Lisbon and immigrated to Jerusalem via Damascus. He composed several books, including a well-known commentary on the writings of the Ari, Kol BeRamah [A Voice in Ramah], an abridged version of the intention of the Ari, called Nagid UMetzaveh [A Leader and Commander], Olat HaTamid [The Continual Burnt Offering], on the intention of Rav Chaim Vital, TzemachTzadik [The Righteous Tzemach].
Rabbi Yitzchak Isaac Yehuda Yechiel Safrin
of Komarno (1806-1874)
Rabbi Yitzchak Yehiel of Komarno became well-known for his extensive knowledge of the hidden and revealed Torah. He was educated in the surroundings of the Seer of Lublin, Rabbi Naftali of Rufshitz, and Rabbi Abraham Mordechai of Pintschov. He composed many books including Maase Ereg [Woven Work] and Atzei Eden [Trees of Eden] on the Mishnah, The Face of the Elder on Masechet Shekalim, The Treasure of Life and the Hall of Blessing, Notzer Hesed [Treasuring Mercy], Zohar Chai [Living Brightness], and Netiv Mitzvotecha [Path of Your Commandments].
Rabbi Yitzhak Ben Tzvi Ashkenazi
(...-1806)
Rabbi Yitzhak Ben Tzvi Ashkenazi was the chief justice in Hodorov, Poland, and later an adjudicator in Levov. His famous book Purity of Sanctity, which discusses Masechet Zevachim, proved his depth in the laws and in Kabbalah. He composed another book called The Candlelight.
Rabbi Yitzhak Luria Ashkenazi,
Ari (1534-1572)
The Ari disclosed and developed a new method of studying Kabbalah, called “The Lurianic method.” The Ari was born in Jerusalem. His father died when he was young, and his mother traveled with him to her brother Rabbi Mordechai Francis, who lived in Egypt. The Ari studied Torah and Kabbalah with Rabbi David Even Zimra, Radbaz, and with Rabbi Bezalel Ashkenazi. He was secluded himself for seven years, studying The Book of Zohar.
In 1570, the Ari went to the Kabbalist city of Safed. The great Kabbalists, old and young, who realized the greatness and uniqueness of his method, wished to study with him, but he turned some of them down. For a year and a half, he taught his students the principles of his method, yet before his passing, he instructed them not to engage in it. Only his student Rav Chaim Vital was allowed to teach his method, since he was the only one who understood it properly.
The Ari taught his students orally and did not leave any notes after him. However, Chaim Vital, who documented his words meticulously, composed the books The Tree of Life and Eight Gates to the Ari, based on the notes. The writings of Chaim Vital were buried next to him but members of his family later dug them out and published his books.
The Ari composed several poems, found in the Siddur [prayer book], including Azamer BeShvachin [I Will Sing in Praise], Bnei Heichala [Sons of the Palace], Asader LiSeudata [I Will Set Up for the Meal].
Rabbi Israel Baal Shem Tov,
[The Baasht (Baal Shem Tov)] (1698-1760)
The Baal Shem Tov, Rabbi Israel Ben Eliezer Baal Shem Tov, founder of the Hassidic movement, was born in Poland. His parents died when he was young. In his youth he used to seclude himself in the mountains and study Kabbalah. He wandered around Poland gathering Jews in whom he found a special drive to know the purpose of their lives. After teaching them how to attain spirituality, he founded and led the Hassidic movement with their help.
The Baasht stood out in his unique and charismatic personality. He introduced a new kind of Jewish leadership, the Tzadik [a righteous man]. The Baasht also fashioned the model of a group uniting around a charismatic leader who gives personal guidance to each of his disciples.
The Hassidut emphasized the intention of the heart and the enthusiasm more than studiousness and erudition. It emphasized the person's attainment of the Creator by himself or with the help of a Tzadik. His words were quoted in many books, including Keter Shem Tov [The Crown of Shem Tov], Meirot Einayim [Opening the Eyes], and Tzava'at Ribash [The Will of Ribash].
Rabbi Menahem Mendel of Kotzk
(1787-1859)
Rabbi Menahem Mendel of Kotzk was born in Goraj near Lublin, Poland. He grew up in a home of opposers to Hassidism, yet already from a young age was drawn to Hassidut and studied with Rabbi Simcha Bonim of Pshischa, Rabbi Yaacov Yitzhak, the Jew from Pshischa, and the Seer of Lublin.
He was poignant and original in his approach and became well-known for his precise and razor-sharp sayings. He demanded a true and serious approach toward spirituality, focusing the majority of one’s effort on the goal of life. Among his well-known disciples were Rabbi Yitzhak Meir of Gur, author of Hidushei HaRIM [Innovations of the RIM], Rabbi Hanoch Hanich of Alexander, Rabbi Ze'ev Wolf of Starikov, and Rabbi Yehiel Meir of Gustanin.
His many students continued his unique path in Hassidic congregations that they founded throughout Eastern Europe. In 1840, the Rabbi of Kotzk isolated himself and refused to come in contact even with his disciples. Many books were written about him and his sharp tongue and discernments, such as, “There is none so whole as a broken heart,” in A bush burns in Kotzk.
Rabbi Menahem Nachum Twersky
of Chernobyl (1730-1798)
Rabbi Menahem Nachum Twersky of Chernobyl was educated in the Lita [Lithuania] Seminary and was influenced by the teachings of the Ari. He was a student of The Baal Shem Tov, and after his demise he studied with the Sayer of Mazritch. He was an Admor [a great teacher] of the first generation of Hassidut. Rabbi Twersky founded the Hassidut dynasty in Chernobyl. His books are The Light of the Eyes on the Torah, Let the Heart Rejoice, literal interpretations of the Gemarah according to Kabbalah.
Rabbi Moshe Ben Maimon,
Rambam [Maimonides] (1138-1204)
Maimonides was among the greatest adjudicators and Jewish philosophers in the Middle Ages, a leader and a physician. He was born in Kordova, Spain, and moved to North Africa. After writing the composition Kiddush Hashem [Sanctification of the Creator], he was forced to leave with the Anusim [“forced ones”: terminology applied to a Jew who has been forced to abandon Judaism against one’s will] and arrived in Israel.
As a result of the difficult living conditions in the country, he moved to Egypt, serving as physician and counselor to one of the most important rulers. His status allowed him to serve as governor of the Egyptian Jews.
Among his compositions are Hilchot Deot, Hilchot Avoda Zara [Laws of Idolatry],Guide to the Perplexed, Perush Mishnahyot [Commentaries on the Mishnah], Mishneh Torah, Sefer HaMitzvot [The Book of Commandments], Teshuvot BeHalacha [Answers on Laws], “Letters of Maimonides, the Glory of the Generation (Q&A).”
Rabbi Moshe Chaim Ephraim of Sadilkov
(1748-1800)
Rabbi Mosh Haim Efraim, author of the book The Banner of the Camp of Ephraim, was the Baal Shem Tov's grandson and became known as the Rabbi of Sadilkov. He was born in the town of Mazhibozh and studied with his grandfather, the Baasht. After the passing of the Baasht, he studied with the Sayer of Mazritch and Rabbi Yaacov Yosef from Polana. Afterward, he settled in Sadilkov. His book, The Banner of the Camp of Ephraim, is one of the seminal books of Hassidut, accurately describing the words of the Baal Shem Tov.
Rabbi Moshe Chaim Luzato,
The Ramchal (1707-1747)
Rabbi Moshe Chaim Luzato, The Ramchal, was a great and well-known Kabbalist from Italy. He was born in Padua and was particularly outstanding from a very young age in his rare memory and ability for deep study.
At only fourteen years of age, he had already the entirety of the writings of the Ari's. At the age seventeen, he wrote his first book and was fiercely opposed by Rabbi Hagiz. In 1740, he published his renowned book Mesilat Yesharim[Path of the Just]. In 1743, he immigrated to The Land of Israel and died of a plague in Acre along with his entire family. He composed some forty books among which are Klalei Pitchei Hochmah VeDaat [Rules of the Doors of Wisdom and Knowledge], Shaarey Ramchal [Gates of Ramchal], and Adir BaMarom [The Mighty One on High].
Rabbi Moshe Cordovero,
Ramak (1522-1570)
Rabbi Moshe Cordovero, Ramak, was among the sages in the land of Israel. He lived most of his life in Safed and was a student of Rabbi Yosef Karo, and the Kabbalist Rabbi Shlomo Elkabetz, composer of the psalm Go My Beloved.
At age twenty six, he wrote his first book Pardes Rimonim [Orchard of Pomegranates], which discusses the wisdom of Kabbalah. Prior to the arrival of the Ari in Safed, Ramak was considered the greatest Kabbalist of Safed. Among his students were Eliahu di Vidash, author of Resheet Hochma [Beginning of Wisdom], and Rabbi Abraham Glenati, composer of Kol Bochim [Voice of the Wailing].
Ramak published several other books, the most well-known being Ohr Yakar [Precious Light], an extensive and profound commentary on The Zohar. Some of that extensive commentary was published with the title Shiur Komah [A Measure of Height], an introduction to the interpretation of the Idrot [Assemblies] of The Zohar. Additional books are Ohr Ne'erav [Evening Light], Sefer HaGirushin [Book of the Expelled], Sefer Ilima Rabati [Book of the Great Ilima], A Prayer unto Moses, and Know the God of Your Father.
Rabbi Nachman of Breslev
(1772-1810)
Rabbi Nachman of Breslev was Baal Shem Tov’s grandson. In 1798 he immigrated to Israel, yet, because of Napoleon’s wars, he returned to the Ukraine, settled in the town of Uman and taught Hassidut through tales and stories. Some of his compositions are Talks of Rabbi Nachman, and Likutey Moharan [Collections of Teacher Rabbi Nachman].
Rabbi Pinchas Eliyahu Ben Meir
(...-1802)
Rabbi Pinchas Eliyahu Ben Meir composed Sefer HaBrit [Book of the Covenant] anonymously. He also composed Mitzvot Tovim[Commandment of the Good], discussing the purpose of the Mitzvot [commandments], Beit Yotzer [Birthplace], which interprets Sefer Yetzira [Book of Craetion], Matmonei Mistorim [Hidden Treasures], concerning letter combinations and an interpretation of Rabbi Emanuel Chai Riki’s book Mishnat Hassidim [Teaching of the Hassidim].
Rabbi Tzvi Hirsh Eichenstein of Ziditshov
(1763-1831)
Rabbi Tzvi Hirsh Eichenstein of Ziditshov, son of Rabbi Yitzhak Isaac of Safrin, Hungary, was a student of The Seer of Lublin’s and was considered one of his heirs. Among others, he studied with the Sayer of Kuznitch, Rabbi Elimelech of Lizhanski, Rabbi Moshe Leib of Sassov, Rabbi Yehoshua Hashil of Afta, and Rabbi Baruch of Mazbozh. He was well-known in the revealed Torah and the concealed Torah and composed the books Ateret Tzvi [A Crown of Glory], a commentary on The Zohar, Sur MeRa VeAseh Tov [Depart from Evil and Do Good], Beit Yisrael [The House of Israel], and Pri Kodesh Hilulim [Holy Fruit for Praising].
Rabbi Shalom Ben Moshe Buzzaglo
(…-1780)
Rabbi Shalom Ben Mosh Buzzaglo, a famous Kabbalist from Marrakesh, Morocco, a student of Rabbi Abraham Ben Mordechai Azulai, composed several Kabbalah books. Among them are Kisse HaMelech [The King’s Throne], a commentary on the Tikkunim [corrections] of TheZohar, Hadrat Melech [King’s Glory], a commentary on The Zohar divided into two Chapters: Hod Melech [The King’s Majesty] on Safra de Tzniuta, and Mikdash Melech [The King’s Temple] and Kisse Melech [The King’s Throne] on the Tikkunim.
Rabbi Simcha Bonim of Pshischa
(1767-1827)
Rabbi Simch Bonim of Pshischa, the son of Rabbi Yitzhak HaMaggid, was born in Vadislav. In his youth, he studied with Rabbi Mordechai Bennett. He was introduced to Hassidut and became one of the leaders of the second generation of the Hassidut. He was a student of the Seer of Lublin, Rabbi Yaacov Yitzhak and the Holy Jew, Rabbi Yaacov Yitzhak of Pashicsa.
He continued the path of the Holy Jew, delving and expanding the path of Hassidut. His well-known students were Rabbi Menachem Mendel of Kotzk, Rabbi Yitzcak of Vorka, Hidushey HaRim—the Rabbi of Gur, Rabbi Yehezkel of Kozmir, Rabbi Chanoch Hanich of Alexander, Rabbi Abraham of Tscheknov, and others.
His teachings were published in his students’ books, Hedvat Simcha [Joy of Gladness], Ramatim Tzofim [The Low of Joy],Ramathaim-Zophim, and Kol Simcha [The Voice of Joy].
Rabbi Shimon Ben Lavi
(1488-1588)
Kabbalist Rabbi Shimon Ben Lavi was born in Spain and was exiled with his family in 1492. He roamed Portugal and in 1497, moved to Fez in Morocco. In 1549 he moved to Tripoli, where he became the Community Rabbi. Rabbi Shimon Ben Lavi composed poems on Rashbi and two books, Ketem Paz [Spot of Gold], and Yad Ne’eman [Faithful Hand].
Rabbi Shimon Bar Yochai,
Rashbi
Rabbi Shimon Bar Yochai, Rashbi, one of the most prominent student of Rabbi Akiva, is mentioned in the Mishnah numerous times as “Rabbi Shimon,” and is well known in the revealed Torah and the concealed Torah.
Rashbi grew up in Yavne and was ordained by Rabbi Akiva and Rabbi Yehuda Ben Baba to teach the wisdom of Kabbalah to the future generations. Following Rabbi Akiva’s incarceration, the government was informed that he was speaking against them so he hid in a cave in Peki’in for thirteen years, along with his son, Rabbi Elazar.
Following his exit from the cave, Rabbi Shimon gathered nine students, went with them into a small cave in Meron, and with their help, he wrote The Book of Zohar, the seminal book of Kabbalah. However, he instructed his student Rabbi Abba to do the actual writing, since he knew that he was the only one who could conceal what needed to be concealed and reveal what was revealed. When he composed The Book of Zohar, he knew it was intended for future generations so he hid it.
The Book of Zohar was written in a special language, the language of Midrash, Aramaic. In TheZohar itself, it is mentioned that Aramaic is the posterior of Hebrew. TheZohar is regarded as the foundation of the wisdom of Kabbalah. It describes a clear and formulated method to attain spirituality and is taught by people the world over. Rav Yehuda Ashlag’s authoritative commentary, Perush HaSulam [The Sulam Commentary], enables its study in our time as well.
Rabbi Shimon Bar Tzemach Duran, Rashbatz
(1361-1444)
Rabbi Shimon Bar Zemach Duran, Rashbatz, was a physician, a poet and a Kabbalist. He studied with Rabbi Nissim Ben Reuven and with Rabbi Yitzhak Bar Sheshet (the Ribash). He lived in Spain, but moved to Algeria during the persecution in Spain in 1391. Rashbatz composed many books and was outstanding in its questions and answers which were published in the three volumes of Tashbetz [Crossword]. Additional books include Magen Avot [The Fathers’ Shield], Ohr HaChaim [Light of Life], Leviat Chen [A Graceful Wreath], Yavin Shmua [Understanding Rumors], and Zohar HaRakia [Brightness of the Firmament].
Rabbi Schneier Zalman of Laddi,
The Old Admor (1745-1813)
Rabbi Schneier Zalman of Laddi, the old Admor, founded Hassidut Habad, despite the Vilna Gaon’s (GRA) objection. Rabbi Schneier studied Kabbalah and Hassidut with the Sayer of Mazritch and founded his method in Hassidut called HaBaD, (Hochma, Bina, Daat) after the passing of the Sayer of Mazritch.
During the war between Russia and France in 1812, he convinced his students to support Russia and later had to escape the vengeance of the French. He composed the books Shulhan Aruch HaRav [The Rav’s Set Table] an updated book of laws for the Habad Hassidim, which is still in use today, Siddur Tefila [Prayer Book], Likutei Torah [Collections of Torah], and The Tanya [Tanya Rabbati], describing the foundations of his method.