If men learn this, it will implant forgetfulness in their souls; they
will cease to exercise memory because they rely on that which is
written, calling things to remembrance no longer from within
themselves, but by means of external marks. What you have discovered
is a recipe not for memory, but for reminder. And it is no true wisdom
that you offer your disciples, but only its semblance, for by telling
them of many things without teaching them you will make them seem to
know much, while for the most part they know nothing, and as men
filled, not with wisdom, but with the conceit of wisdom, they will be
a burden to their fellows.
-- Plato. "Phaedrus."
The Collected Dialogues of Plato,
Edited by Edith Hamilton and Huntington Cairns
Translated by Lane Cooper. Princeton University Press (1961).