Genetics is to biology what atomic theory is to physics. Its principle is clear: that inheritance is based on particles and not on fluids. Instead of the essence of each parent mixing, with each child the blend of those who made him, information is passed on as a series of units. The bodies of successive generations transport them through time, so that a long-lost character may emerge in a distant descendant. The genes themselves may be older than the species that bear them.

I always feel like our descendants—they're going to be upset with us for wrecking the planet anyway—but they're really going to be mad that we didn't even bother to take a good picture. [On the importance of thorough research of even a little ant species.]

I do not know whether my distrust of men of science is congenital or acquired, but I think I should have transmitted it to descendants.

In Cairo, I secured a few grains of wheat that had slumbered for more than thirty centuries in an Egyptian tomb. As I looked at them this thought came into my mind: If one of those grains had been planted on the banks of the Nile the year after it grew, and all its lineal descendants had been planted and replanted from that time until now, its progeny would to-day be sufficiently numerous to feed the teeming millions of the world. An unbroken chain of life connects the earliest grains of wheat with the grains that we sow and reap. There is in the grain of wheat an invisible something which has power to discard the body that we see, and from earth and air fashion a new body so much like the old one that we cannot tell the one from the other.…This invisible germ of life can thus pass through three thousand resurrections.

It may be said of some very old places, as of some very old books, that they are destined to be forever new. The nearer we approach them, the more remote they seem: the more we study them, the more we have yet to learn. Time augments rather than diminishes their everlasting novelty; and to our descendants of a thousand years hence it may safely be predicted that they will be even more fascinating than to ourselves. This is true of many ancient lands, but of no place is it so true as of Egypt.

Paris ... On this side of the ocean it is difficult to understand the susceptibility of American citizens on the subject and precisely why they should so stubbornly cling to the biblical version. It is said in Genesis the first man came from mud and mud is not anything very clean. In any case if the Darwinian hypothesis should irritate any one it should only be the monkey. The monkey is an innocent animal—a vegetarian by birth. He never placed God on a cross, knows nothing of the art of war, does not practice lynch law and never dreams of assassinating his fellow beings. The day when science definitely recognizes him as the father of the human race the monkey will have no occasion to be proud of his descendants. That is why it must be concluded that the American Association which is prosecuting the teacher of evolution can be no other than the Society for Prevention of Cruelty to Animals.
[A cynical article in the French press on the Scopes Monkey Trial, whether it will decide “a monkey or Adam was the grandfather of Uncle Sam.”]

That only Galileo’s physical finger is preserved but the descendants of his techniques thrive is also symbolic of the transitoriness of personal existence in contrast to the immortality of knowledge.

The conception of the atom stems from the concepts of subject and substance: there has to be “something” to account for any action. The atom is the last descendant of the concept of the soul.

The epoch of intense cold which preceded the present creation has been only a temporary oscillation of the earth’s temperature, more important than the century-long phases of cooling undergone by the Alpine valleys. It was associated with the disappearance of the animals of the diluvial epoch of the geologists, as still demonstrated by the Siberian mammoths; it preceded the uplifting of the Alps and the appearance of the present-day living organisms, as demonstrated by the moraines and the existence of fishes in our lakes. Consequently, there is complete separation between the present creation and the preceding ones, and if living species are sometimes almost identical to those buried inside the earth, we nevertheless cannot assume that the former are direct descendants of the latter or, in other words, that they represent identical species.

The only part of evolution in which any considerable interest is felt is evolution applied to man. A hypothesis in regard to the rocks and plant life does not affect the philosophy upon which one's life is built. Evolution applied to fish, birds and beasts would not materially affect man's view of his own responsibilities except as the acceptance of an unsupported hypothesis as to these would be used to support a similar hypothesis as to man. The evolution that is harmful—distinctly so—is the evolution that destroys man’s family tree as taught by the Bible and makes him a descendant of the lower forms of life. This … is a very vital matter.

The outlook seems grim. Natural selection under civilized conditions may lead mankind to evolve towards a state of genetic overspecialization for living in gadget-ridden environments. It is certainly up to man to decide whether this direction of his evolution is or is not desirable. If it is not, man has, or soon will have, the knowledge requisite to redirect the evolution of his species pretty much as he sees fit. Perhaps we should not be too dogmatic about this choice of direction. We may be awfully soft compared to paleolithic men when it comes to struggling, unaided by gadgets, with climatic difficulties and wild beasts. Most of us feel most of the time that this is not a very great loss. If our remote descendants grow to be even more effete than we are, they may conceivably be compensated by acquiring genotypes conducive to kindlier dispositions and greater intellectual capacities than those prevalent in mankind today.
[Co-author with American statistician Gordon Allen.]

The worst thing that will probably happen—in fact is already well underway—is not energy depletion, economic collapse, conventional war, or the expansion of totalitarian governments. As terrible as these catastrophes would be for us, they can be repaired in a few generations. The one process now going on that will take millions of years to correct is loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us.

Thus the radio elements formed strange and cruel families in which each member was created by spontaneous transformation of the mother substance: radium was a “descendant” of uranium, polonium a descendant of radium.

When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think, as we lay stone on stone, that a time is to come when those stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, “See! This our father did for us.”

Why, then, are we surprised that comets, such a rare spectacle in the universe, are not known, when their return is at vast intervals?. … The time will come when diligent research over long periods will bring to light things which now lie hidden. A single lifetime, even though entirely devoted to the sky, would not be enough for the investigation of so vast a subject … And so this knowledge will be unfolded only through long successive ages. There will come a time when our descendants will be amazed that we did not know things that are so plain to them …. Many discoveries are reserved for ages still to come, when memory of us will have been effaced. Our universe is a sorry little affair unless it has in it something for every age to investigate … Nature does not reveal her mysteries once and for all. Someday there will be a man who will show in what regions comets have their orbit, why they travel so remote from other celestial bodies, how large they are and what sort they are.