People are always talking about originality, but what do they mean? As soon as we are born, the world begins to work upon us, and this goes on to the end.

What we don't understand we don't possess.

Where confidence is wanting, the most beautiful flower in the garland of love is missing.

Should I not be proud, when for twenty years I have had to admit to myself that the great Newton and all the mathematicians and noble calculators along with him were involved in a decisive error with respect to the doctrine of color, and that I among millions was the only one who knew what was right in this great subject of nature?

Nothing is worth more than this day.

The destiny of any nation at any given time depends on the opinion of its young people, those under twenty-five.

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.