Charles DARWIN, 1859: The Origin of Species, Ch. 14 (London: Murrey, 1859), p. 489.

Darwin Online, http://darwin-online.org.uk/Variorum/1859/1859-489-dns.html

As all the living forms of life are the lineal descendants of those which lived long before the Silurian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence we may look with some confidence to a secure future of equally inappreciable length. And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection.