Attainment of the Torah Begins with “Sod” (Secret) and Ends with “Peshat” (Literal)
The concealed Torah implies that the Creator hides in the Torah, hence the name, “the Torah of the hidden.” Conversely, it is called “revealed” because the Creator is revealed by the Torah.
Therefore, the Kabbalists said, and we also find it in the prayer book of the Vilna Gaon (GRA), that the order of attainment of the Torah begins with the concealed and ends with the revealed (Peshat). This means that through the appropriate labor, where one first delves into the Torah of the hidden, he is thus granted the revealed Torah, the literal [revealed meaning]. Thus, one begins with the concealed, called Sod (secret), and when he is rewarded, he ends in the literal [when everything becomes completely clear to him].
– Baal HaSulam, “Introduction to The Study of the Ten Sefirot,” Item 103