The environment is everything that isn't me.

Children don’t heed the life experiences of their parents, and nations ignore history. Bad lessons always have to be learned anew.

Wisdom is not a product of schooling but of the lifelong attempt to acquire it.

The scientist is activated by a wonder and awe before the mysterious comprehensibility of the universe which is yet finally beyond his grasp. In its profoundest depths it is inaccessible to man.

This is a question too difficult for a mathematician. It should be asked of a philosopher"(when asked about completing his income tax form)

I have tried 99 times and have failed, but on the 100th time came success.

If you can't explain what you are doing to a nine-year-old, then either you still don't understand it very well, or it's not all that worthwile in the first place.