If agricultural land be left uncultivated, in a few years the jungle returns, and signs are not lacking that a similar danger is always lying in wait for the fields of thought, which, by the labour of three hundred years, have been cleared and brought into cultivation by men of science. The destruction of a very small percentage of the population would suffice to annihilate scientific knowledge, and lead us back to almost universal belief in magic, witchcraft and astrology.

Great discoveries are made accidentally less often than the populace likes to think. Commenting on how an accident led to the discovery of X-rays.

It seemed as though the main framework had been put together once and for all, and that little remained to be done but to measure physical constants to the increased accuracy represented by another decimal point.

The fundamental concepts of physical science, it is now understood, are abstractions, framed by our mind, so as to bring order to an apparent chaos of phenomena.

There seems no limit to research, for as been truly said, the more the sphere of knowledge grows, the larger becomes the surface of contact with the unknown.

If agricultural land be left uncultivated, in a few years the jungle returns, and signs are not lacking that a similar danger is always lying in wait for the fields of thought, which, by the labour of three hundred years, have been cleared and brought into cultivation by men of science. The destruction of a very small percentage of the population would suffice to annihilate scientific knowledge, and lead us back to almost universal belief in magic, witchcraft and astrology.