Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

Wrongly do men cry out against experience and with bitter re- proaches accuse her of deceitfulness. Let experience alone, and rather turn your complaints against your own ignorance, which causes you to be so carried away by your vain and insensate desires as to expect from experience things which are not within her power!

It is so easy to hide our ignorance under such expressions as the plan of creation or unity of design, etc., and to think that we give an explanation when we only restate a fact.

No human investigation can be called real science if it cannot be demonstrated mathematically.

To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science.

Freedom of thought is best promoted by the gradual illumination of men's minds which follows from the advance of science.