In all stages of what may be described fairly as legal development, philosophy has been a useful servant. But in some it has been a tyrannous servant, and in all but form a master. It has been used to break down the authority of outworn tradition, to bend authoritatively imposed rules that admitted of no change to new uses which changed profoundly their practical effect, to bring new elements into the law from without and make new bodies of law from these new materials, to organize and systematize existing legal materials and to fortify established rules and institutions when periods of growth were succeeded by periods of stability and of merely formal reconstruction. Such have been its actual achievements. Yet all the while its professed aim has been much more ambitious. It has sought to give us a complete and final picture of social control. It has sought to lay down a moral and legal and political chart for all time. It has had faith that it could find the everlasting, unchangeable legal reality in which we might rest, and could enable us to establish a perfect law by which human relations might be ordered forever without uncertainty and freed from need of change. Nor may we scoff at this ambitious aim and this lofty faith. They have been not the least factors in the power of legal philosophy to do the less ambitious things which in their aggregate are the bone and sinew of legal achievement. For the attempt at the larger program has led philosophy of law incidentally to do the things that were immediately and practically serviceable, and the doing of these latter, as it were _sub specie aeternitatis_, has given enduring worth to what seemed but by-products of philosophical inquiry.