Tools, weapons, utensils, buildings, gardens and cultivated fields, are all products of human intelligence. They are material arrangements embodying in outward and visible form trains of ideas which have passed through human minds. Flowing from human intelligence these objects appeal to human intelligence. The child, in learning their nature and use, rethinks the thoughts which gave them being. In this way, as much as by the help of language and direct imitation, the ideas of one generation are transmitted to the next to be by it further developed, so that from comparatively small beginnings human civilisation may grow like an avalanche ever accumulating and retaining new material as it advances. Now the lower animals do not in this manner create an environment for themselves by their own intelligence. Bees, ants, nestbuilding birds, beavers and other animals with definite constructive tendencies may be said in part to make their own environment. But they do not do so in execution of designs framed by themselves. Their constructions do not embody trains of ideas directed to the attainment of foreseen ends. As their work does not arise from trains of ideas in the first instance, so it does not awaken trains of ideas in the successive generations which repeat the same activities. Each new generation is born with the instinctive aptitudes and propensities of its progenitors and repeats their doings in the same undesigning way. On the other hand, the works of man, as they arise from ideational thought, so they arouse ideational thought. The same understanding which was needed for their production is needed for their reproduction. Hence the educational influence of an environment moulded by human hands to embody human designs does not affect the animals which dwell with man. The human intelligence incorporated in the products of human industry is intelligible only to a mind essentially akin to the human mind. The external world as an ideal construction is a social product. It must therefore be independent of the individual subject in the same manner and degree as social organisation in general is independent of its individual members. There is thus introduced a new factor in the constitution of external reality, — the social factor. The ideal combinations which arise in the individual mind can only become permanent parts of the ideal structure representing the real world if they are entertained by other minds also, and so become current in the society to which the individual belongs. Besides the verification of ideal combinations by actual experience by means of corresponding perceptual experiences, another kind of verification is required. Social endorsement is necessary. On the other hand, ideal combinations which are generally current in society tend to maintain themselves in the mind of the individual, even though he has never himself verified them, and even though his own personal experience is unfavourable to them rather than otherwise. Now and then a person is met with who dares to deny that the earth is round; there is nothing in his direct personal experience to show the roundness; on the contrary, so far as he can observe it, it seems to be flat. Now such a person is generally regarded as a "crank"; he is generally spoken of as a harmless kind of lunatic; and what is more important, he is so spoken of by multitudes of persons who know much less about the matter than himself. The reason is that he is maintaining his own individual ideas against the vast work of ideal construction which has been built up by the cooperative thinking of many generations. It is true that this ideal structure is in process of constant development; and that as it grows it rectifies itself, excluding ideal combinations which had previously formed integral parts of it, and receiving into itself others which it has previously rejected. But the earthflattener does not appear as a representative of this advance: he puts himself forward, or is supposed to do so, merely as an individual setting up his own private thoughts in antagonism to the social product. The experts who are the accredited representatives of the development of the general system of ideas in this direction, scout his pretensions: he therefore figures as an isolated individual appearing in the strength of his own private judgment in opposition to the established social order, and he is therefore regarded by society much in the same way as a lunatic or criminal, the only difference being that he is considered to be harmless and amusing.

This is a case taken from our own complex society, in which ideal construction is so vast in its extent and so diversified that there is no single person who can hold more than a fragment of it, and its various branches are assigned to the keeping of special guardians. These complex conditions give a certain freedom of play to the individual, which is absent in more simple organisations. In more primitive communities, such as we find among savages, the general stock of ideas is assimilated by each individual, and all are equally its guardians. Thus the pressure of society upon the individual is incomparably more coercive. Any private rebellion against inherited and accepted tradition would be resented and suppressed with great speed and certainty. Thus primitive societies are intensely conservative and remarkably unanimous in their modes of thought. Each thinks as the rest think, and dares not persevere in any innovation which does not find general acceptance. Ideal activity is on the whole more occupied in finding reasons to justify tradition, or to explain its apparent in consistency with actual experience, than in further developing and improving the ideal scheme which has been handed down from generation to generation.