The nature of the human mind is such that unless it is stimulated by images of things acting upon it from without, all remembrance of them passes easily away.
We must say that there are as many squares as there are numbers.
And yet it moves.
Measure what is measurable, and make measurable what is not so.
If I were again beginning my studies, I would follow the advice of Plato and start with mathematics.
I give infinite thanks to God, who has been pleased to make me the first observer of marvelous things.
