When the boy begins to understand that the visible point is preceded by an invisible point, that the shortest distance between two points is conceived as a straight line before it is ever drawn with pencil and paper...the fountain of all thought has been opened to him...the philosopher can reveal him nothing new, as a geometrician he has discovered the basis of all thought.

Certain faults are necessary for the existence of the individual. We would resent it if old friends were to get rid of certain peculiarities.

The greater the knowledge, the greater the doubt.

What you desire when young, you have in abundance when old.

I consider him of no account who esteems himself just as the popular breath may chance to raise him.

If a man knows where to get good advice, it is as though he could supply it himself.

Wisdom is only found in truth.