Socrates: I cannot help feeling, Phaedrus, that writing is unfortunately like painting; for the creations of the painter have the attitude of life, and yet if you ask them a question they preserve a solemn silence. And the same may be said of speeches. You would imagine that they had intelligence, but if you want to know anything and put a question to one of them, the speaker always gives one unvarying answer. And when they have been once written down they are tumbled about anywhere among those who may or may not understand them, and know not to whom they should reply, to whom not: and, if they are maltreated or abused, they have no parent to protect them; and they cannot protect or defend themselves.

Phaedrus: That again is most true.

Socrates: Is there not another kind of word or speech far better than this, and having far greater power-a son of the same family, but lawfully begotten?

Phaedrus: Whom do you mean, and what is his origin?

Socrates: I mean an intelligent word graven in the soul of the learner, which can defend itself, and knows when to speak and when to be silent.

Phaedrus: You mean the living word of knowledge which has a soul, and of which written word is properly no more than an image?

Socrates: Yes, of course that is what I mean.

Plato, Phaedrus 275d-276a

For I am covetous of something better, the possession of which I frequently enjoy within me before I commence to body it forth in intelligible words: and then when my capacities of expression prove inferior to my inner apprehensions, I grieve over the inability which my tongue has betrayed in answering to my heart. For it is my wish that he who hears me should have the same complete understanding of the subject which I have myself; and I perceive that I fail to speak in a manner calculated to effect that, and that this arises mainly from the circumstance that the intellectual apprehension diffuses itself through the mind with something like a rapid flash, whereas the utterance is slow, and occupies time, and is of a vastly different nature, so that, while this latter is moving on, the intellectual apprehension has already withdrawn itself within its secret abodes.

Augustine, On the Catechism of Unlearned 2.3