Problems are not stop signs, they are guidelines.

There is always room at the top.

We aim above the mark to hit the mark.

If opportunity doesn't knock, build a door.

The true method of knowledge is experiment.

Knowledge is knowing that we cannot know.

Progress is impossible without change, and those who cannot change their minds cannot change anything.

Knowledge has to be improved, challenged, and increased constantly, or it vanishes.

If you don't have time to do it right, when will you have time to do it over?

If you don't like something, change it. If you can't change it, change your attitude.