Most scientific conceptions have been based on the method of spatial analysis, i.e. the reduction, where possible, of a thing to its smallest spatial elements. Physics, biology, and psychology have all lacked the equipment to describe what makes the atom, organism, or the pattern function as a unit, and how we are to know if some group is a unit or not. The analytical method is fully developed, but we lack even the basis for a synthetic treatment. This leads some hard-headed scientists of the materialistic school who will ‘stand no nonsense’ to assert that there is no such thing as ‘synthesis’, that this is a mystical idea left over from primitive anthropomorphism. Yet to any mind that is guided not by prejudice but by a simple search for truth, the fact of synthesis is obvious, though not yet properly formulated. Here modern physics can supply a clue. Analysis is the method required in a search for instantaneous spatial structure; the synthetic method which we need must deal with the temporal history and behaviour of systems. The fact that the human being reacts in the ways he does to a tune as a whole is evidence of something in his history, that he has heard the tune often under certain emotional surroundings. The unity of any synthesis, whole, or organism is not an instantaneous fact explicable in terms of structure, for we can recognize this unity only from a continued observation over a period of time. Physics can invent one law to describe the approach of the two hydrogen atoms to form a molecule, and in doing so treats the two together as a unit. This suggests that the fact of organic unity is to be defined and formulated in terms of an irreversible law which governs the system as a whole. Thus a group of atoms, cells, or any other elements is to be called a unit when, and only when, one irreversible law can be found which expresses the behaviour of the different elements as contributing towards some common end, like the formation of the molecule in the case of the hydrogen atoms. We can now draw a practical conclusion for the future of psychology, which is in great need of a moral principle to guide its treatment of disintegrated human personality. On the analogy of the two atoms, a human being is to be considered as a unity when his whole behaviour displays continuous co-ordination towards some end. But there is an important difference in the two cases: the atoms move towards an end which we know because it has already happened in history, whereas man’s development is creative, that is it proceeds towards an end we cannot know exactly before it comes into being. Thus the parent or psychologist need not trouble if he cannot understand what his child or subject is aiming towards: so long as some consistency and harmony of functioning is apparent, the ‘end’ can be left to nature to look after, because such harmony _means_ that the organism is tending towards some ultimate condition.