For I tell you there is far more serious risk in the purchase of doctrines than in that of eatables. When you buy victuals and liquors you can carry them off from the dealer or merchant in separate vessels, and before you take them into your body by drinking or eating you can lay them in your house and take the advice of an expert whom you can call in, as to what is fit to eat or drink and what is not, and how much you should take and when; so that in this purchase the risk is not serious. But you cannot carry away doctrines in a separate vessel: you are compelled, when you have handed over the price, to take the doctrine in your very soul by learning it, and so to depart either an injured or a benefited man.
From Pythagoras, Plato
