Philo of Alexandria · 1717 of 1726
Appendix 2 · From the same author, on Exod 23:18.
Instead of saying leavened bread must not come among the things which are offered, but all things which are brought as a sacrifice or an offering must be unleavened, he intimates two most necessary things by an obscure and symbolical expression; one being to despise pleasure, for leaven is the seasoning of food and not food itself; and the other being that it is not right for men to be elated, because of being puffed up by vain self-conceit; for each is a wicked state, and pleasure and selfconceit are both the offspring of one mother, deceit.
The blood of the sacrifices is a proof of a soul making its offerings to God; and it is not in accordance with the divine law that things which will not unite should be mingled together.