These wishes, however, are seldom expressed directly. So foreign are they to our civilised selves that even in sleep our habits of thinking assert themselves and exercise some check upon what shall be expressed; but they are generally distorted almost beyond recognition by the substitutions of more acceptable ideas for crude images of instinctive needs, and as the subconscious mind links ideas together according to their superficial or accidental associations, it will be seen that strange and tangled dramas will be acted out upon the stage of the mind in an effort to represent the fulfilment of some primitive instinctive wish. Modern methods of psychological research make much use of dreams in the effort to investigate the levels of the mind to which we have no direct access, and psychotherapy uses the same method in order to trace the disorders of the mind to their cause. For if the train of thought which the mind has followed in its progression from a crude instinctive, often physical, wish to the completed dream-drama be traced back again from the images of the dream to the underlying ideas which gave rise to them, we can lay bare the hidden springs of motive and character; hence the great use that has been made of the method of dream analysis in modern psychotherapy. It is interesting to note that the delusions of lunatics are constructed upon exactly the same principles as the phantasies of our castles in the air; they also represent the fulfilment of wishes that have been denied their realisation, and have achieved their ultimate form through the same primitive methods of thinking that are responsible for our dreams; in fact, they may be looked upon as a phantasy which has progressed a step nearer realisation than the day-dream. The symptoms of the hysteric have a similar origin, but represent the wishes of dissociated complexes instead of the wishes of the whole personality as happens in insanity. Thus we may see that, should our desires be denied expression in our lives, they will construct dream castles for themselves during sleep in which we may temporarily dwell as monarch of all we survey; and should these desires be very imperative, should a large part of our nature be involved in them, then the dream may overflow into waking consciousness, and we shall live among our own subjective mind pictures, instead of among objective realities, and act out the part we have assigned ourselves in the dream-drama, to the consternation of onlookers who pronounce us insane. The lunatic, however, is not irrational, he is absolutely rational if once his premises be granted, for he carries the logical deductions from these premises to their ultimate conclusion. And once it be realised that some fundamental and essentially natural wish lies at the root of these phantasies which we see him acting out, then we shall see that the clue to the treatment of insanity lies in these wishes and the region of the mind that gives rise to them.