We have to understand that the world can only be grasped by action, not by contemplation. The hand is more important than the eye ... The hand is the cutting edge of the mind.

All science is the search for unity in hidden likenesses.

The most remarkable discovery ever made by scientists is science itself. The discovery must be compared in importance with the invention of cave-painting and of writing.

When Da Vinci wanted an effect, he willed, he planned the means to make it happen: that was the purpose of his machines. But the machines of Newton ... are means not for doing but for observing. He saw an effect, and he looked for its cause.

But nature - that is, biological evolution - has not fitted man to any specific environment. On the contrary, ... he has a rather crude survival kit; and yet -this is the paradox of the human condition - one that fits him to all environments. Among the multitude of animals which scamper, fly, burrow and swim around us, man is the only one who is not locked into his environment. His imagination, his reason, his emotional subtlety and toughness, make it possible for him not to accept the environment but to change it.

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.

Man is a singular creature. He has a set of gifts which make him unique among the animals, so that unlike them, he is not a figure in the landscape, he is the shaper of the landscape.