In Euclid each proposition stands by itself; its connection with others is never indicated; the leading ideas contained in its proof are not stated; general principles do not exist. In modern methods, on the other hand, the greatest importance is attached to the leading thoughts which pervade the whole; and general principles, which bring whole groups of theorems under one aspect, are given rather than separate propositions. The whole tendency is toward generalization. A straight line is considered as given in its entirety, extending both ways to infinity, while Euclid is very careful never to admit anything but finite quantities. The treatment of the infinite is in fact another fundamental difference between the two methods. Euclid avoids it, in modern mathematics it is systematically introduced, for only thus is generality obtained.

No video, no photographs, no verbal descriptions, no lectures can provide the enchantment that a few minutes out-of-doors can: watch a spider construct a web; observe a caterpillar systematically ravaging the edge of a leaf; close your eyes, cup your hands behind your ears, and listen to aspen leaves rustle or a stream muse about its pools and eddies. Nothing can replace plucking a cluster of pine needles and rolling them in your fingers to feel how they’re put together, or discovering that “sedges have edges and grasses are round,” The firsthand, right-and-left-brain experience of being in the out-of-doors involves all the senses including some we’ve forgotten about, like smelling water a mile away. No teacher, no student, can help but sense and absorb the larger ecological rhythms at work here, and the intertwining of intricate, varied and complex strands that characterize a rich, healthy natural world.

Philosophers and psychiatrists should explain why it is that we mathematicians are in the habit of systematically erasing our footsteps. Scientists have always looked askance at this strange habit of mathematicians, which has changed little from Pythagoras to our day.

The essence of modernity is that progress no longer waits on genius; instead we have learned to put our faith in the organized efforts of ordinary men. Science is as old as the race, but the effective organization of science is new. Ancient science, like placer mining, was a pursuit of solitary prospectors. Nuggets of truth were found, but the total wealth of knowledge increased slowly. Modern man began to transform this world when he began to mine the hidden veins of knowledge systematically.

The history of science, like the history of all human ideas, is a history of irresponsible dreams, of obstinacy, and of error. But science is one of the very few human activities—perhaps the only one—in which errors are systematically criticized and fairly often, in time, corrected. This is why we can say that, in science, we often learn from our mistakes, and why we can speak clearly and sensibly about making progress there. In most other fields of human endeavour there is change, but rarely progress ... And in most fields we do not even know how to evaluate change.

We are in the presence of a recruiting drive systematically and deliberately undertaken by American business, by American universities, and to a lesser extent, American government, often initiated by talent scouts specially sent over here to buy British brains and preempt them for service of the U.S.A. … I look forward earnestly to the day when some reform of the American system of school education enables them to produce their own scientists so that, in an amiable free trade of talent, there may be adequate interchange between our country and theirs, and not a one-way traffic.

We must not put mistakes into programs because of sloppiness, we have to do it systematically and with care.