• On the theory of natural selection we can clearly understand the full meaning of that old canon in natural history, “Natura non facit saltum.” This canon, if we look only to the present inhabitants of the world, is not strictly correct, but if we include all those of past times, it must by my theory be strictly true.

    Charles Darwin (1869). “On the Origin of Species by Means of Natural Selection: Or the Preservation of Favoured Races in the Struggle for Life”, p.183