The most malicious kind of hatred is that which is built upon a theological foundation.

Wisdom is not mathematical, nor astronomical, nor zoological when it talks too much of any one thing it ceases to be itself. There are wise physicists, but wisdom is not physical there are wise physicians, but wisdom is not medical.

There are but few saints amongst scientists, as among other men, but truth itself is a goal comparable with sanctity.

From the humanistic point of view every human achievement is unforgettable and immortal in its essence, even if it is replaced by a better one.

Greek culture is pleasant to contemplate because of its great simplicity and naturalness, and because of the absence of gadgets, each of which is sooner or later a cause of servitude.

Erudition without pedantry is as a rare as wisdom itself.

A deed happens in a definite place at a definite time, but if it be sufficiently great and pregnant, its virtue radiates everywhere in time and space.

science is the most revolutionary force in the world.

All men are our brothers. As far as the discovery of the truth is concerned, they are all working for the same purpose they may be separated by the accidents of space and time, and by the exigencies of race, religion, nationality, and other groupings from the point of view of eternity they are working together.

The rationalism of the creative minds was tempered by abundant fantasies, and the supreme beauty of the monuments was probably spoiled by the circumambient vanities and ugliness in a few cases the Greeks came as close to perfection as it was possible to do, yet they were human and imperfect.

Perhaps the main, as well as the least obvious, achievement of the Middle Ages, was the creation of the experimental spirit, or more exactly its slow incubation. This was primarily due to Muslims down to the end of the twelfth century, then to Christians.

If we are generous enough, we can stretch our souls everywhere and everywhen else. If we succeed in doing so, we shall discover that our present embraces the past and the future and that the whole world is our province.

The history of science should not be an instrument to defend any kind of social or philosophic theory it should be used only for its own purpose, to illustrate impartially the working of reason against unreason, the gradual unfolding of truth, in all its forms, whether pleasant or unpleasant, useful of useless, welcome or unwelcome.

My main interest... is the love of truth, whether pleasant or not. Truth is self-sufficient, and there is nothing to which it can be subordinated without loss. When truth is made subservient to anything else, however great (say religion), it becomes impure and sordid.