No matter how much we learn, there is always more knowledge to be gained. In this connection I am reminded of a short poem that has been in my mind over the years. It reads as follow: I used to think I knew I knew. But now I must confess. The more I know I know I know I know I know the less.
It is by discourse that men associate, and words are imposed according to the apprehension of the vulgar. And therefore the ill and unfit choice of words wonderfully obsesses the understanding. Nor do the definitions or explanations wherewith in some things learned men are wont to guard and defend themselves, by any means set the matter right. But words plainly force and overrule the understanding, and throw all into confusion, and lead men away into innumerable and inane controversies and fancies.
Real wisdom is not the knowledge of everything, but the knowledge of which things in life are necessary, which are less necessary, and which are completely unnecessary to know.
Erudition, like a bloodhound, is a charming thing when held firmly in leash, but it is not so attractive when turned loose upon a defenseless and unerudite public.
The mind of the thoroughly well-informed man is a dreadful thing. It is like a bric-à-brac shop, all monsters and dust, with everything priced above its proper value.
[Not enough is known about solid geometry] and for two reasons: in the first place, no government places value on it; this leads to a lack of energy in the pursuit of it, and it is difficult. In the second place, students cannot learn it unless they have a teacher. But then a teacher can hardly be found.