De Agricultura

But it is not every memory which is good, but only that which is exerted on good subjects, since it is a most pernicious thing that what is bad should not be forgotten; on which account, with a view to perfection, it is necessary that the hoofs should be parted, in order that so the faculty of memory, being divided into two sections, the word which flows through the mouth may divide the lips, as being things which nature has made of a two-fold character, and may also separate the advantageous species of memory from that which is mischievous.