Problems are only opportunities in disquise.

Ninety percent of our lives is governed by emotion.

I am sure that one secret of a successful teacher is that he has formulated quite clearly in his mind what the pupil has got to know in precise fashion. He will then cease from half-hearted attempts to worry his pupils with memorizing a lot of irrelevant stuff of inferior importance.

One main factor in the upward trend of animal life has been the power of wandering.

The race that does not value trained intelligence is doomed.

Science repudiates philosophy. In other words, it has never cared to justify its truth or explain its meaning.

To come very near to a true theory, and to grasp its precise application, are two different things, as the history of science teaches us. Everything of importance has been said before by someone who did not discover it.