E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Eat not the Heart.
This is the 30th Symbol in the Protreptics of Iamblichus. Pythagoras forbade judges and priests to eat animal food at all, because it was taking away life. Other persons he did not wholly forbid this food, but he restricted them from eating the brain (the seat of wisdom) and the heart (the seat of life).