Our ideas of morality, religion, or politics form complexes, as do our desires and disappointments. An ardent photographer or naturalist is possessed of a complex concerning his hobby, and this complex tends to turn his thoughts in the corresponding direction. If a keen botanist and an equally keen amateur photographer are travelling by train each views the scenery according to his complex: the one might note the trees and plants, their flowering or bursting into leaf, and how they vary with the soil, and might speculate as to what finds a closer view might produce; the other sees the same objects, but is busy composing pictures, thinking out distances and exposures, or differences of light and shade. The man with 'a bee in his bonnet' gives an example of a single powerful complex; but all our thinking is a matter of complexes except on those rare occasions when logic alone is concerned, such as the consideration of a problem of mathematics. Scientific men are prone to believe that their mind-work is purely logical; so it is, up to a certain point, and the more exact the science the less room there is for thinking in complexes; but the reception of a new theory is always opposed by those whose firmly established complexes are offended by it. The aim of scientific training is to eliminate complex thinking and substitute logic, and in the exact sciences this is practically attained; but as soon as the trained man forsakes his laboratory or workshop methods he is at the mercy of his complexes and becomes the ordinary rationalising human being. There is a great difference between a complex, such as photography, of which the influence is recognised and admitted by its owner, and another, such as a political one, where the influence is strongly denied. The latter is kept in a logic-tight compartment and reconciled to the reason by rationalisations. Instincts have their abode in the unconscious and differ from acquired influences in being inborn and common to the race. It is difficult to determine what emotions and desires are truly inborn, as Benjamin Kidd shows in a valuable personal observation.[3] [Footnote 3: _The Science of Power_, p. 284. Methuen & Co., 1918.] He found a wild duck's nest as the young birds had just emerged from the egg, the mother-bird flying off at his approach. He took the young birds out of the nest and they showed no fear, nestling from time to time on his feet. Then he moved away and saw the mother-bird return with 'the great terror of man' upon her; next he approached the group again, but the mother-bird flew away with warning quacks and the little ones scattered to cover. He found one of them, but it was now 'a wild transformed creature trembling in panic which could not be subdued'.