The importance of personality in the historic life of peoples is manifest in periods when social conditions accelerate the movement of social life. Personality, like every other force, reaches its maximum when it encounters resistance, in conflict and in rivalry--when it fights--hence its great value in friendly rivalry of nations in industry and culture, and especially in periods of natural calamities or of enemies from without. Since the fruits of individual development contribute to the common fund of social values, it is clear that societies and peoples which, other things being equal, possess the most advanced and active personalities contribute most to the enrichment of civilization. It does not seem necessary to demonstrate that the pacific competition of nations and their success depends on the development of the personalities which compose them. A nation weak in the development of individualities, of social units which compose it, could not defend itself against the exploitation of nations composed of personalities with a superior development. D. BIOLOGICAL AND SOCIAL HEREDITY 1. Nature and Nurture[75] We have seen that the scientific position in regard to the transmissibility of modifications should be one of active scepticism, that there seems to be no convincing evidence in support of the affirmative position, and that there is strong presumption in favor of the negative. A modification is a definite change in the individual body, due to some change in "nurture." There is no secure evidence that any such individual gain or loss can be transmitted as such, or in any representative degree. How does this affect our estimate of the value of "nurture"? How should the sceptical or negative answer, which we believe to be the scientific one, affect our practice in regard to education, physical culture, amelioration of function, improvement of environment, and so on? Let us give a practical point to what we have already said. a) Every inheritance requires an appropriate nurture if it is to realize itself in development. Nurture supplies the liberating stimuli necessary for the full expression of the inheritance. A man's character as well as his physique is a function of "nature" and of "nurture." In the language of the old parable of the talents, what is given must be traded with. A boy may be truly enough a chip of the old block, but how far he shows himself such depends on "nurture." The conditions of nurture determine whether the expression of the inheritance is to be full or partial. It need hardly be said that the strength of an (inherited) individuality may be such that it expresses itself almost in the face of inappropriate nurture. History abounds in instances. As Goethe said, "Man is always achieving the impossible." Corot was the son of a successful milliner and prosperous tradesman, and he was thirty before he left the draper's shop to study nature.