If you always put limit on everything you do, physical or anything else, it will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.

I know that many will call this useless work.

Shun those studies in which the work that results dies with the worker.

Those men who are inventors and interpreters between Nature and Man, as compared with boasters and declaimers of the works of others, must be regarded and not otherwise esteemed than as the object in front of a mirror, when compared with its image seen in the mirror.

I am not to blame for putting forward, in the course of my work on science, any general rule derived from a previous conclusion.

Let no man who is not a Mathematician read the elements of my work.