This week's Torah portion describes the laws of buying and selling. Our sages teach us that a person can not acquire something that has not yet 'entered this world'. However, a promise to donate something that does not yet exist must be kept when it does come into existence.
There is a Kabbalistic principle that the beginning is wedged in the end, and the end is wedged in the beginning, so what is the connection between the end of the book of Leviticus and its beginning?