Francis Galton, answered from the texts and cited to the page.
The difficulty with the question is that men speak as if the two were separable in practice, when they are in truth almost never found apart. Man is so educable an animal that it is difficult to distinguish between that part of his character which has been acquired through education and circumstance, and that which was in the original grain of his constitution.1
I coined the phrase to name the two contributions precisely because the confusion between them had muddied every discussion of human difference I had encountered. Nature is the original endowment — the constitutional grain, the inherited tendency of intellect and disposition that a man brings into the world with him. What I mean by natural ability is those qualities of intellect and disposition which urge and qualify a man to perform acts that lead to reputation: not capacity without zeal, nor zeal without capacity, but a nature which, when left to itself, will climb the path that leads to eminence and has strength to reach the summit.2
Nurture is everything that acts upon that endowment from without — early culture, education, circumstance, the accidents of position. The relation between them is best caught by an image. There is a current in a stream; there are also the particular bends and obstructions the water meets on its course. The accidents of circumstance correspond to those bends; the natural tendency is the current, and it inevitably asserts itself.3
Carlyle put something close to this before me, and I was glad to find the sentiment: an acorn, he observed, may by favourable or unfavourable influences of soil be nursed into a doddered dwarf bush or a high-towering tree, but no combination of circumstances will nurse it into a cabbage.4 The species is fixed; the flourishing of the individual within its kind is what nurture governs.
What the evidence compels me to add is that the apparent power of nurture is often the power of nature working through the nurturers. Those teachings that conform to the natural aptitudes of the child leave far more enduring marks than others — and both the teachings and the natural aptitudes of the child are usually derived from the same parents, who understand the ways of one another more intimately than strangers of different blood can.5
The child's disposition is evoked by its parents, not formed by them; and the marks left by the instructions of a foster-mother are soon sponged clean away.6 The cuckoo, reared through hundreds of generations by foster-parents whose language is a chirp and a twitter, leaves its birthplace the moment it is able and finds its own kith and kin, and its note remains singularly correct.7
Nurture, in that case, accomplished nothing against the grain of nature. I do not dismiss nurture; I assign it its proper share, which is the share of the soil to the seed. The seed is the thing that matters most.
Man is so educable an animal that it is difficult to distinguish between that part of his character which has been acquired through education and circumstance, and that which was in the original grain of his constitution.Inquiries into Human Faculty and Its Development
By natural ability, I mean those qualities of intellect and disposition, which urge and qualify a man to perform acts that lead to reputation... a nature which, when left to itself, will, urged by an inherent stimulus, climb the path that leads to eminence, and has strength to reach the summit.Hereditary Genius
The one element, that varies in different individuals, but is constant in each of them, is the natural tendency; it corresponds to the current in the stream, and inevitably asserts itself.Inquiries into Human Faculty and Its Development
an acorn might, by favourable or unfavourable influences of soil and climate, be nursed into a cabbage, or the cabbage-seed into an oak. Nevertheless... hereby we have either a doddered dwarf bush, or a high-towering, wide-shadowing tree.English Men of Science
Those teachings that conform to the natural aptitudes of the child leave much more enduring marks than others. Now both the teachings and the natural aptitudes of the child are usually derived from its parents.Inquiries into Human Faculty and Its Development
Its disposition is 'educated' by them, in the true sense of the word; that is to say, it is evoked, not formed by them... The marks left on the memory by the instructions of a foster-mother are soon sponged clean away.Inquiries into Human Faculty and Its Development
the cuckoo cannot or will not adopt that language, or any other of the habits of its foster-parents... So utterly are its earliest instructions in an alien bird-language neglected, and so completely is its new education successful, that the note of the cuckoo tribe is singularly correct.Inquiries into Human Faculty and Its Development