My mitochondria comprise a very large proportion of me. I cannot do the calculation, but I suppose there is almost as much of them in sheer dry bulk as there is the rest of me. Looked at in this way, I could be taken for a very large, motile colony of respiring bacteria, operating a complex system of nuclei, microtubules, and neurons for the pleasure and sustenance of their families, and running, at the moment, a typewriter.

I can say, if I like, that social insects behave like the working parts of an immense central nervous system: the termite colony is an enormous brain on millions of legs; the individual termite is a mobile neurone.

The drive to be useful is encoded in our genes. But when we gather in very large numbers, as in the modern nation-state, we seem capable of levels of folly and self-destruction to be found nowhere else in all of nature. But if we keep at it and keep alive, we are in for one surprise after another. We can build structures for human society never seen before, thoughts never heard before, music never heard before.

Of all celestial bodies within reach or view, as far as we can see, out to the edge, the most wonderful and marvellous and mysterious is turning out to be our own planet earth. There is nothing to match it anywhere, not yet anyway.

Society evolves not by shouting each other down, but by the unique capacity of unique, individual human beings to comprehend each other.

If an idea cannot move on its own, pushing it doesn't help; best to let it lie there.

The greatest achievements in the science of this [twentieth] century are themselves the sources of more puzzlement than human beings have ever experienced. Indeed, it is likely that the twentieth century will be looked back at as the time when science provided the first close glimpse of the profundity of human ignorance. We have not reached solutions; we have only begun to discover how to ask questions.