"The policy or advantage of [immigration] taking place in a body (I mean the settling of them in a body) may be much questioned; for, by so doing, they retain the language, habits, and principles (good or bad) which they bring with them. Whereas by an intermixture with our people, they, or their descendants, get assimilated to our customs, measures, and laws: in a word, soon become one people."

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If we look round the world, there seem to be not above six distinct varieties in the human species, each of which is strongly marked, and speaks the kind seldom to have mixed with any other. But there is nothing in the shape, nothing in the faculties, that shows their coming from different originals; and the varieties of climate, of nourishment, and custom, are sufficient to produce every change.

— Oliver Goldsmith