Concerning love and fear, it is known that fear precedes love. The reason for this is in order for one to be able to observe Torah and Mitzvot [commandments] out of love, meaning that he will feel the taste of pleasure in Torah and Mitzvot, which will cause him to love the Torah and Mitzvot.
But one who observes Torah and Mitzvot because of fear, at that time he still does not feel the pleasure of Torah and Mitzvot, but observes because of the fear of the Creator. That is, he is afraid that the Creator might punish him if he does not observe Torah and Mitzvot.
It follows that then, all his work is because of fear of the Creator, meaning that the body gives him thoughts of doubts about the fear. Hence, each time, he must grow stronger in faith in the Creator until he is rewarded with permanent faith.
Afterward, he is rewarded with observing Torah and Mitzvot because of love, meaning to feel the flavor of pleasure in Torah and Mitzvot.
Conversely, if the Creator were to let him serve Him with love from the beginning, by feeling pleasure in Torah and Mitzvot, he would not need faith in the Creator, like those whose vitality comes only from corporeal pleasures and they observe all the manners of nature such as eating and drinking. They do not need faith in the Creator and observe all of nature’s commandments because of the feeling of pleasure.
Likewise, if they felt pleasure in Torah and Mitzvot, everyone would be observing the Torah and Mitzvot because of pleasure and not because it is the commandment of the Creator. In other words, they would not need to believe in the Creator and would be able to receive the pleasure of Torah and Mitzvot without union with the Creator. Hence, a concealment was placed on Torah and Mitzvot not to reveal the pleasure of Torah and Mitzvot until after one is awarded through fear with permanent faith in the Creator.