According to the theory that evolution is progress, the progress or evolution of humanity obeys the same laws, is impelled by the same forces, and follows the same line as the evolution of organisms in general; and consists accordingly in increasing adaptation to the environment. Imperfect adaptation manifests itself whenever a man's impulses or desires move him to perform acts which are immediately or eventually prejudicial to his own or to society's existence. Adaptation will be perfect when all acts which are necessary for the existence of the individual and of the society are pleasant in themselves--when not only going to the dentist's will be a duty, but the extraction will be a pleasure desired for its own sake. Though Mr. Huxley maintained that it was a misleading illusion to lead people to expect any such state of untroubled happiness, he was far from denying that progress has been made in the past by man, or from despairing of further progress in the future. But progress does not, according to him, consist in adaptation to environment; it is not effected by means of the struggle for existence; it neither obeys the same laws, nor is impelled by the same forces, nor follows the same lines as organic evolution in general. Nor does it consist in the substitution of personal pleasure for a sense of duty as the motive of action: on the contrary, it consists in a fuller and fuller recognition of the claims of others. The idea that evolution means progress, and by its very nature necessarily results in perfection, owes much of its popularity to the fallacious interpretation given to the phrase "survival of the fittest." In any scientific use of the phrase, "fittest" simply means "fittest to survive." But in popular usage it is supposed to mean "ideally or ethically best." But the fittest to survive are not necessarily the ideally best: they are, scientifically speaking, simply those best adapted to the circumstances and conditions under which they live. And the circumstances and conditions, the environment, may or may not be favourable to the survival of the ethically or æsthetically best: they may be favourable to the growth of weeds and to the destruction of beautiful flowers, in which case the cosmic process will wipe out the beautiful flowers, and the movement of evolution will be æsthetically retrogressive, not progressive.