=Physical and Social Inheritance.=—The influence of inheritance is exerted from two quarters which may be distinguished by calling them _physical_ and _social_. [Sidenote: (_a_) Physical.] By the former we mean the influence exerted upon human beings by the bodily and mental traits which are handed down to them by their own parents. Not all the characteristics of parents are transmitted to their children but mainly those which the parents themselves have inherited. Traits or qualities which have been acquired by the parents during their own lives do not ordinarily descend to their children.[5] Parents who are born feeble-minded will in all probability have feeble-minded children; but parents who acquire through education a high degree of learning and culture cannot transmit any of this to their children by inheritance. There is no royal road to learning. Some of us are born with better or worse possibilities than others, but we are all born illiterate. [Sidenote: (_b_) Social.] The other form of inherited influence is called our social heritage because it represents the whole accumulation of knowledge, habits, and expedients which have come down to us by the social process of teaching and learning. Each generation of mankind is enormously dependent upon its social inheritance; without it everything that we now call civilization would collapse in a very short time. Each generation takes over all the knowledge possessed by the one which went before; each generation adds something to this stock of knowledge, habits, and expedients for the benefit of the generation which comes after it. Each generation, if it is to live happily, must adapt this social inheritance to its own particular needs. [Sidenote: The two kinds of environment:] =Physical and Social Environment.=—The other great influence is that of environment. By physical environment we mean the conditions of nature and society in which man lives, moves, and has his being. Physical environment includes the geographic, climatic, and other natural conditions which surround the people. [Sidenote: (_a_) Physical.] These conditions have an important influence upon the trend of human development and they are not, for the most part, under man’s control. Man must adapt himself and his ways of life to them. In cold climates he must wear warm clothing, provide artificial heat in houses, and consume warmth-giving food. Groups of men must everywhere mould their occupations to the character of the soil, the natural resources, and the other conditions of the physical environment in which they live. It is because of differences in physical environment that the Southern states developed cotton-culture on a large scale and employed slave labor, while the Northern states gave their attention to farming and industry with free labor.