Evolution quote

As all sciences are based upon facts, known, or to be known from experience, so are they, in their early state of developement [sic], matters of pure observation. It is only when we have acquired the power of generalising these facts, when such generalisations agree among themselves and with every thing we see or know of nature, that the theory of a science becomes either absolutely demonstrative, or approaches so near to certainty, by the force of analogical reasoning, that it is not contradicted by anything known. The case of natural history, then, is precisely this; in its early stages it is a science of observation; in its latter, it is one of demonstration. [William Swainson. 1834. Preliminary discourse on the study of natural history. London: Longman, Rees, Orme, Brown, Green and Longman, page 105.]

Swainson is one of the infamous “Quinarians”, but his discussion on natural classification is influential. It is clear that Darwin had read him and his history of classification in the preceding chapter.