I know quite certainly that I myself have no special talent; curiosity, obsession and dogged endurance, combined with self-criticism, have brought me to my ideas.
I know too well that these arguments from probabilities are imposters, and unless great caution is observed in the use of them, they are apt to be deceptive.
I told myself, "Lincoln, you can never make a lawyer if you do not understand what demonstrate means." So I left my situation in Springfield, went home to my father's house, and stayed there till I could give any proposition in the six books of Euclid at sight. I then found out what "demonstrate" means, and went back to my law studies.
There are branches of learning and education which we must study merely with a view to leisure spent in intellectual activity, and these are to be valued for their own sake; whereas those kinds of knowledge which are useful in business are to be deemed necessary, and exist for the sake of other things.
The same things are best both for individuals and for states, and these are the things which the legislator ought to implant in the minds of his citizens.
We must know, if only in order to learn not to know. The supreme lesson of human consciousness is to learn how not to know. That is, how not to interfere.
The youthful brain should in general not be burdened with things ninety-five percent of which it cannot use and hence forgets again... In many cases, the material to be learned in the various subjects is so swollen that only a fraction of it remains in the head of the individual pupil, and only a fraction of this abundance can find application, while on the other hand it is not adequate for the man working and earning his living in a definite field.