In the same way, in the sexual relations of two women, one always plays the male and the other the female part, a fact of deepest significance. Here we encounter, in a most unexpected fashion, the fundamental relationship between the male and female elements. In spite of all sexually intermediate conditions, human beings are always one of two things, either male or female. There is a deep truth underlying the old empirical sexual duality, and this must not be neglected, even although in concrete cases there is not a necessary harmony in the anatomical and morphological conditions. To realise this is to make a great step forward and to advance towards most important results. In this way we reach a conception of a real “being.” The task of the rest of this book is to set forth the significance of this “existence.” As, however, this existence is bound up with the most difficult side of characterology, it will be well, before setting out on our adventurous task, to attempt some preliminary orientation. The obstacles in the way of characterological investigation are very great, if only on account of the complexity of the material. Often and often it happens that when the path through the jungle appears to have been cleared, it is lost again in impenetrable thickets, and it seems impossible to recover it. But the greatest difficulty is that when the systematic method of setting out the complex material has been proceeded with and seems about to lead to good results, then at once objections of the most serious kind arise and almost forbid the attempt to make types. With regard to the differences between the sexes, for instance, the most useful theory that has been put forward is the existence of a kind of polarity, two extremes separated by a multitude of intermediate conditions. The characterological differences appear to follow this rule in a fashion not dissimilar to the suggestion of the Pythagorean, Alcmæon of Kroton, and recalling the recent chemical resurrection of Schelling’s “Natur-philosophie.” But even if we are able to determine the exact point occupied by an individual on the line between two extremes, and multiply this determination by discovering it for a great many characters, would this complex system of co-ordinate lines really give us a conception of the individual? Would it not be a relapse to the dogmatic scepticism of Mach and Hume, were we to expect that an analysis could be a full description of the human individual? And in a fashion it would be a sort of Weismannistic doctrine of particulate determinants, a mosaic psychology.