For it is not for knowledge to enlighten a soul that is dark of itself, nor to make a blind man see.

Her business is not to find a man's eyes, but to guide, govern, and direct them, provided he have sound feet and straight legs to go upon.

Knowledge is an excellent drug, but no drug has virtue enough to preserve itself from corruption and decay, if the vessel be tainted and impure wherein it is put to keep.
Such a one may have a sight clear enough who looks asquint, and consequently sees what is good, but does not follow it, and sees knowledge, but makes no use of it.

Plato's principal institution in his Republic is to fit his citizens with employments suitable to their nature.

Nature can do all, and does all.