[In relation to business:] Invention must be its keynote—a steady progression from one thing to another. As each in turn approaches a saturated market, something new must be produced.

Analogy is a wonderful, useful and most important form of thinking, and biology is saturated with it. Nothing is worse than a horrible mass of undigested facts, and facts are indigestible unless there is some rhyme or reason to them. The physicist, with his facts, seeks reason; the biologist seeks something very much like rhyme, and rhyme is a kind of analogy.... This analogizing, this fine sweeping ability to see likenesses in the midst of differences is the great glory of biology, but biologists don't know it.... They have always been so fascinated and overawed by the superior prestige of exact physical science that they feel they have to imitate it.... In its central content, biology is not accurate thinking, but accurate observation and imaginative thinking, with great sweeping generalizations.

I think that space flight is a condition of Nature that comes into effect when an intelligent species reaches the saturation point of its planetary habitat combined with a certain level of technological ability... I think it is a built-in gene-directed drive for the spreading of the species and its continuation.

Judged superficially, a progressive saturation of the germ plasm of a species with mutant genes a majority of which are deleterious in their effects is a destructive process, a sort of deterioration of the genotype which threatens the very existence of the species and can finally lead only to its extinction. The eugenical Jeremiahs keep constantly before our eyes the nightmare of human populations accumulating recessive genes that produce pathological effects when homozygous. These prophets of doom seem to be unaware of the fact that wild species in the state of nature fare in this respect no better than man does with all the artificality of his surroundings, and yet life has not come to an end on this planet. The eschatological cries proclaiming the failure of natural selection to operate in human populations have more to do with political beliefs than with scientific findings.

The cause of rain is now, I consider, no longer an object of doubt. If two masses of air of unequal temperatures, by the ordinary currents of the winds, are intermixed, when saturated with vapour, a precipitation ensues. If the masses are under saturation, then less precipitation takes place, or none at all, according to the degree. Also, the warmer the air, the greater is the quantity of vapour precipitated in like circumstances. ... Hence the reason why rains are heavier in summer than in winter, and in warm countries than in cold.

The condensed air becomes attached to [the metallic calx], and adheres little by little to the smallest of its particles: thus its weight increases from the beginning to the end: but when all is saturated, it can take up no more.

The name of medicine is thought to have been given from 'moderation', modus, that is, from a due proportion, which advises that things be done not to excess, but 'little by little', paulatim. For nature is pained by surfeit but rejoices in moderation. Whence also those who take drugs and antidotes constantly, or to the point of saturation, are sorely vexed, for every immoderation brings not health but danger.

The usefulness of mathematics in furthering the sciences is commonly acknowledged: but outside the ranks of the experts there is little inquiry into its nature and purpose as a deliberate human activity. Doubtless this is due to the inevitable drawback that mathematical study is saturated with technicalities from beginning to end.

The vacuum-apparatus requires that its manipulators constantly handle considerable amounts of mercury. Mercury is a strong poison, particularly dangerous because of its liquid form and noticeable volatility even at room temperature. Its poisonous character has been rather lost sight of during the present generation. My co-workers and myself found from personal experience-confirmed on many sides when published—that protracted stay in an atmosphere charged with only 1/100 of the amount of mercury required for its saturation, sufficed to induce chronic mercury poisoning. This first reveals itself as an affection of the nerves, causing headaches, numbness, mental lassitude, depression, and loss of memory; such are very disturbing to one engaged in intellectual occupations.