Our Gemara on Amud Beis conceptualizes the prohibition of charging interest as any financial compensation that is an incentive for the lender to delay payment of his debt. In essence, time is money, and the charging of interest is an enactment of the value that having access to money at one time over another brings profit. Assuming that the rate of interest is not exploitative, the Torah asks us to run against a normal instinct to manage money wisely and be extraordinarily charitable and trusting in God’s providence by forgoing access to funds that could be invested.

Mei Hashiloach (I:Vayikra, Behar 2) notes that the scripture juxtaposes three mitzvos in Vayikra (ch. 25): Shemittah (not working or profiting from the land during the seventh year), the freeing of slaves in the Yovel year, and the prohibition of taking interest. Shemitta represents a loss of control over the land, as once every seven years it is essentially ownerless. The freeing of the slaves during the Yovel year reminds us that we cannot really own another person. And the prohibition against charging interest teaches us that we do not even own time itself. (Though one can own a canaanite slave, the expression of non-ownership of a person is exemplified in the Halacha of a Jewish slave. This is just like how one may charge interest from a gentile, but still the legal requirement of non-usury from a Jew, teaches the concept of non-ownership in principle. A mitzvah might teach its lesson in an emblematic manner, but not require it broadly.) 

All three of these laws are the Torah’s message to free ourselves from our conception of control, and particularly control over the spheres of time, our land and our bodies, which are very human habitual delusions.