The dignity of man is vindicated as much by the thinker and poet as by the statesman and soldier.

Science advances, not by the accumulation of new facts, but by the continuous development of new concepts.

Science emerges from the other progressive activities of man to the extent that new concepts arise from experiments and observations, and that the new concepts in turn lead to further experiments and observations.

Education is what is left after all that has been learnt is forgotten.

The stumbling way in which even the ablest of the scientists in every generation have had to fight through thickets of erroneous observations, misleading generalizations, inadequate formulation, and unconscious prejudice is rarely appreciated by those who obtain their scientific knowledge from textbooks.

Therefore, a grotesque account of a period some thousands of years ago is taken seriously though it be built by piling special assumptions on special assumptions, ad hoc hypothesis [invented for a purpose] on ad hoc hypothesis, and tearing apart the fabric of science whenever it appears convenient. The result is a fantasia which is neither history nor science.

Behold the turtle. He makes progress only when he sticks his neck out.