There must always be a beginning; otherwise, it is impossible to achieve Lishma [for Her sake]. That is, one must believe that in all the corporeal lusts, meaning eating, drinking, and the rest of the lusts, as well as in pleasures found in learning external teachings, control, vengeance, and so forth, as it is written in general, “Envy, lust, and honor take a person out of the world,” in those pleasures there is nothing more than a thin light, as The Zohar says.
Conversely, great lights are deposited in Torah and Mitzvot [commandments], unlike corporeal pleasures, in which only sparks of the light of Kedusha fell.
Hence, Klipot [shells/peels] give one an awakening to enter Kedusha because they want to be rewarded with great lights. This is called Lo Lishma [not for Her sake]. Afterward, from this Lo Lishma, he can be rewarded with Lishma.