The road of social advance is beset with obstacles. The chief are these: (1) The dominance of vegetative needs. These economic factors are so universal and insistent that they are likely at any time to override all other human needs. (2) The insistence of animal impulses, chiefly love and strife. While love promotes unity, it generally produced a limited unity. Moreover, one mode of unity is apt to conflict with other types of unity, and thus lead to intense strife. (3) The mastery of mechanism. Life is easily crushed under the weight of organization; thought, by scholastic pedantry; industry, by economic systems; nationality, by soulless bureaucracy. (4) Anarchism. The remedy for over-organization is not anarchy, for life and society are composed of numbers of conflicting tendencies, which must be controlled by the power of thought. But the exercise of merely individual thought will not suffice. Individual thought is likely to be egocentric, to evade the problems of group life, or to solve them selfishly. (5) Conservatism. An established and successful civilization is in danger of relying too much on its past. It often carries within itself the canker of decay, and frequently lacks any clear vision of higher development. Mackenzie is committed to internationalism. It is no longer fitting for anyone to think of his own country as an exclusive object of devotion. “The earth is our country, and all its inhabitants are our fellow-citizens; and it is only the recognition of this that entitles us to look for any lasting security.” Mackenzie advances beyond the organic analogists when he describes the ways in which society is organic. As a social philosopher he has contributed important pattern-ideas. He has escaped from the foibles of the organic analogy and at the same time indicated the values that lie beneath that concept. This chapter deals with a significant period in the history of social thought. The biology of the time was very faulty and the sociological applications of biological knowledge were consequently of little merit. The early years of the present century were characterized by noteworthy improvements in biological thinking. The facts about the laws of heredity and variation increased in number; a science of heredity was established. The first decade of the present century also marks the rise of the science of eugenics. In a later chapter the contributions of recent scientific biology, and particularly of eugenics, to social thought will be presented. CHAPTER XVII THE SOCIOLOGY OF LESTER F. WARD