When a person uses his hand to give charity, it becomes an extension of God’s hand, as it were.
Despite this lofty status, there is no noticeable impact or change in the giver’s physical hand.
Torah study, by contrast, effects a veritable change in one’s intellect.
His faculty of Hokhma (wisdom) literally becomes a vessel of holiness, its essence transforming from a state of indifference to one of holiness.
When one employs his intellect by thinking about a particular topic of Torah, he is at that very moment thinking God’s thoughts.
This persons faculties of Hokhma, Bina, and Da’at are instantly converted into Godly intellect.
Rabbi Adin Steinsaltz