We gain our ends only with the laws of nature; we control her only by understanding her laws.

Da Vinci was as great a mechanic and inventor as were Newton and his friends. Yet a glance at his notebooks shows us that what fascinated him about nature was its variety, its infinite adaptability, the fitness and the individuality of all its parts. By contrast what made astronomy a pleasure to Newton was its unity, its singleness, its model of a nature in which the diversified parts were mere disguises for the same blank atoms.

Sex was invented as a biological instrument by (say) the green algae. But as an instrument in the ascent of man which is basic to his cultural evolution, it was invented by man himself.

It is very much easier to divide your outlook on the world into two halves, to say that you know this belongs to the daily half and this belongs to the Sunday half.

The richness of human life is that we have many lives, we live the events that do not happen (and some that cannot) as vividly as those that do, and if thereby we die a thousand deaths, that is the price we pay...

All science is the search for unity in hidden likenesses.

Dissent is the mark of freedom, as originality is the mark of independence of mind. … No one can be a scientist … if he does not have independence of observation and of thought.