It is sometimes urged that if this be all that is meant by psychological analysis, alienists have been doing this ever since insanity was first treated, nay, further, doctors have been practising it since the time of Hippocrates. It is pointed out that when a patient is first interviewed by the physician, an inquiry is always made into his mental state and behaviour, and into the presence of delusions and hallucinations or other unusual mental phenomena. His relatives are questioned concerning the relation of his recent behaviour to that at the time when he was considered normal. Now the answer to this assertion is that such an investigation is useful, indispensable in fact, but it cannot be called psychological analysis. The point may become clearer to the untechnical reader if he will imagine for a moment that a carver, skilled in separating the legs and wings from the body of a bird, should claim to be practising anatomy. The anatomist would at once object that while such separation of limbs from trunk is a small detail which sometimes forms part of the anatomist’s task, it can scarcely be called more than a preliminary to his study. For first of all, while to a carver a leg is an ultimate unit, to the anatomist it is, for the naked eye, a collection of bones, muscles, tendons, skin, nerves, veins, arteries, nails and the rest, and, seen through the microscope, a tremendous organisation of infinitely more complex structures. Furthermore, it might be pointed out that merely to separate these more minute structures into their constituent parts and to name them, by no means constitutes the whole of the work of the intelligent anatomist. He wishes to study the inter-relations of these parts, the way in which they work together for the common good of the leg. And lastly, the leg must not be studied only in separation from the trunk, for its functions are subordinate to the requirements of the body as a whole. So, in the same way, to record that a man is suffering from a delusion of persecution or an unreasonable fear of open spaces is merely to “carve up” the condition of his mind. First of all it must be ascertained how far that delusion has interpenetrated with the rest of his mental life; whether, for example, his false belief is restricted to a specific kind of persecution from a particular person, or is a general delusion that everybody and everything in the world is against him. And again, if the delusion is strictly specific, it is important to know whether it has been the cause of secondary false beliefs, produced by rationalisation, to buttress the primary delusion against the inevitable contradiction from facts which it would otherwise suffer.