In the biological evolution, the manifestations of vegetable life do not efface the first glimmerings of the dawn of life that are seen even before in the crystallization of minerals, any more than the manifestations of animal life efface those of vegetable life. The human form of life also permits the continued existence of the forms and links which precede it in the great series of living beings, but, more than this, the later forms only really live in so far as they are the product of the primitive forms and co-exist with them. The social evolution follows the same law: and this is precisely the interpretation of transition periods given by scientific evolutionism. They did not annihilate the conquests of the preceding civilizations, but they preserved, on the contrary, whatever was vital in them and fecundated them for the Renaissance of a new civilization. This law, which dominates all the magnificent development of the social life, equally governs the fate and the parabolic career of all social institutions. One phase of social evolution by following upon another phase eliminates, it is true, the parts that are not vital, the pathological products of preceding institutions, but it preserves and develops the parts that are healthy and vigorous while ever elevating more and more the physical and moral diapason of humanity. By this natural process the great stream of humanity issued from the virgin forests of savage life and developed with majestic grandeur during the periods of barbarism and the present civilization, which are superior in some respects to the preceding phases of the social life, but in many others are marred by the very products of their own degeneracy, as I pointed out in speaking of reactionary varieties of social selection. And, as an example of this, it is certain that the laborers of the contemporaneous period, of the bourgeois civilization have, in general, a better physical and moral life than those of past centuries, but it cannot be denied none the less that their condition as free _wage-workers_ is inferior in more than one particular to the condition of the _slaves_ of antiquity and of the _serfs_ of the Middle Ages. The _slave_ of antiquity was, it is true, the absolute property of his master, of the _free_ man, and he was condemned to well nigh an animal existence, but it was to the interest of his master to assure him daily bread at the least, for the slave formed a part of his estate, like his cattle and horses. Just so, the serf or villein of the Middle Ages enjoyed certain customary rights which attached him to the soil and assured him at the least--save in case of famine--of daily bread.