If I hope to survive, I have to acknowledge the natural selection that goes on when film stocks and cameras are eliminated from the world. And film viewers won't want to watch the same thing over and over again from me.
I Must warn you, Iris, that I'm not a believer. And though I'm sure that the revelations of other men must be a source of infinite satisfaction to them, individually, I shouldn't for one second be so presumptuous as to make a choice among the many thousands of recorded revelations of truth, accepting one at the expense of all the others: I might so easily choose wrong and get into eternal trouble. And you must admit that the selection is wide, and dangerous to the amateur.
One writes such a story [The Lord of the Rings] not out of the leaves of trees still to be observed, nor by means of botany and soil-science; but it grows like a seed in the dark out of the leaf-mold of the mind: out of all that has been seen or thought or read, that has long ago been forgotten, descending into the deeps. No doubt there is much personal selection, as with a gardener: what one throws on one's personal compost-heap; and my mold is evidently made largely of linguistic matter.
My own field of paleontology has strongly challenged the Darwinian premise that life's major transformations can be explained by adding up, through the immensity of geological time, the successive tiny changes produced generation after generation by natural selection.
Even in dialogue, your own style rules your selection. Do not give yourself a blank check of this kind: 'I'll merely reproduce what I think a character like so-and-so would say.' You have to reproduce it in the way your literary premises dictate.
In the most basic way, writers are defined not by the stories they tell, or their politics, or their gender, or their race, but by the words they use. Writing begins with language, and it is in that initial choosing, as one sifts through the wayward lushness of our wonderful mongrel English, that choice of vocabulary and grammar and tone, the selection on the palette, that determines who's sitting at that desk. Language creates the writer's attitude toward the particular story he's decided to tell.
It is clear that the building of models is not a purely mechanical process but requires skill of a high order - not merely mathematical skill but a sensitivity to the relative importance of different factors and a critical, almost an artistic, faculty in the selection of behaviour equations which are reasonable, tentative hypotheses in explaining the behaviour of actual economies.