From W.H. Auden’s 1970 commonplace book A Certain World:

David Hartley offered a vest-pocket edition of his moral and religious philosophy in the formula W = F²/L, where W is the love of the world, F is the fear of God, and L is the love of God. It is necessary to add only this. Hartley said that as one grows older L increases and indeed becomes infinite. It follows then that W, the love of the world, decreases and approaches zero.