Galton was quite well aware that the improved breeding of men is a very different matter from the improved breeding of animals, requiring a different knowledge and a different method, so that the ridicule which has sometimes been ignorantly flung at Eugenics failed to touch him. It would be clearly undesirable to breed men, as animals are bred, for single points at the sacrifice of other points, even if we were in a position to breed men from outside. Human breeding must proceed from impulses that arise, voluntarily, in human brains and wills, and are carried out with a human sense of personal responsibility. Galton believed that the first need was the need of knowledge in these matters. He was not anxious to invoke legislation.[24] The compulsory presentation of certificates of health and good breeding as a preliminary to marriage forms no part of Eugenics, nor is compulsory sterilization a demand made by any reasonable eugenist. Certainly the custom of securing certificates of health and ability is excellent, not only as a preliminary to marriage, but as a general custom. Certainly, also, there are cases in which sterilization is desirable, if voluntarily accepted.[25] But neither certification nor sterilization should be compulsory. They only have their value if they are intelligent and deliberate, springing out of a widened and enlightened sense of personal responsibility to society and to the race. Eugenics constitutes the link between the Social Reform of the past, painfully struggling to improve the conditions of life, and the Social Hygiene of the future, which is authorized to deal adequately with the conditions of life because it has its hands on the sources of life. On this plane we are able to concentrate our energies on the finer ends of life, because we may reasonably expect to be no longer hampered by the ever-increasing burdens which were placed upon us by the failure to control life; while the more we succeed in our efforts to purify and strengthen life, the more magnificent become the tasks we may reasonably hope to attempt and compass.