Our first attempt, urged on by these promptings, is to bring about the realisation of our desires in the external world by means of bodily effort; but should this effort fail to achieve its purpose, or should circumstances deny us the opportunity to make this effort with any hope of success, then the mind often falls back upon a secondary achievement, and images its success in the realms of phantasy and make-believe, where there are no laws of cause and effect to check its operations, and Cinderella in her kitchen constructs a phantasy of the Prince’s ball. She sees her wish acted out to its fulfilment in the theatre of her mind. This factor in our nature influences a large proportion of our mental processes, and is considered to be the chief factor in determining the nature, not only of our dreams, but also of the symptoms of nervous and mental diseases, as will be seen later. During sleep the avenues of the physical senses, whereby impressions reach the mind, are more or less closed, and the ego, which never ceases its activities, is thrown back upon the resources of its memories. Unguided by the reason and judgment, it reviews these, following along the chains of associated ideas according to the laws of memory, which we considered in an earlier chapter. These wanderings, however, though carried out with the illogicality which distinguishes the lower levels of our mind, are not entirely purposeless, being determined by various factors. It may be that physical or sensory impressions, dimly discerned during sleep through the partially closed doors of the senses, will give rise to a train of thought, or the matters upon which the mind has been busied during the day may continue to occupy it in an undirected fashion during sleep; but the dream-determining element to which most attention has been directed in modern psychology is the upsurging of the instinctive wishes which have been denied fulfilment in waking life, so that in our dreams we see realised, as in phantasy, the wishes which have failed to gain realisation in reality, or may even have failed to gain access to our consciousness owing to the operation of the censor which strives to exclude from consciousness all distressing or repulsive matters; for in sleep all our painfully acquired civilisation falls away from us, the higher centres of our being are in abeyance, and our primitive, natural self, controlled but never abolished, expresses its fundamental, untutored desires in their elemental form.