  Darwin himself consistently refers to natural selection as a power of preserving advantageous, and eliminating harmful, variations. As noted in the last section, whether a particular variation is advantageous or harmful is, in once sense of that term, a matter of chance; and whether an advantageous variation is actually preserved by selection is, in another sense of the term, also a matter of chance. For Darwinism, selection is the force or power that biases survival and reproduction in favor of advantageous variations, or to look ahead to the next section, of adaptations. It is this that distinguishes selection from drift.