Some men have claimed for sleep even more than this. 'The night-time of the body,' an ancient writer has said, 'is the day-time of the soul,' and some, who do not absolutely hold the old belief that it is in the dreams of the night that the Divine Spirit most communicates with man, have, nevertheless, believed that the complete withdrawal of our minds from those worldly cares which haunt our waking hours and do so much to materialise and harden our natures is one of the first conditions of a higher life. 'In proportion,' said Swedenborg, 'as the mind is capable of being withdrawn from things sensual and corporeal, in the same proportion it is elevated into things celestial and spiritual.' It has been noticed that often thoughts and judgments, scattered and entangled in our evening hours, seem sifted, clarified, and arranged in sleep; that problems which seemed hopelessly confused when we lay down are at once and easily solved when we awake, 'as though a reason more perfect than reason had been at work when we were in our beds.' Something analogous to this, it has been contended, takes place in our moral natures. 'A process is going on in us during those hours which is not, and cannot be, brought so effectually, if at all, at any other time, and we are spiritually growing, developing, ripening more continuously while thus shielded from the distracting influences of the phenomenal world than during the hours in which we are absorbed in them.... Is it not precisely the function of sleep to give us for a portion of every day in our lives a respite from worldly influences which, uninterrupted, would deprive us of the instruction, of the spiritual reinforcements, necessary to qualify us to turn our waking experiences of the world to the best account without being overcome by them? It is in these hours that the plans and ambitions of our external worldly life cease to interfere with or obstruct the flow of the Divine life into the will.'[75] Without, however, following this train of thought, it is at least sufficiently clear that no small portion of the happiness of life depends upon our sleeping hours. Plato has exhorted men to observe carefully their dreams as indicating their natural dispositions, tendencies, and temptations, and--perhaps with more reason--Burton and Franklin have proposed 'the art of procuring pleasant dreams' as one of the great, though little recognised, branches of the science of life. This is, no doubt, mainly a question of diet, exercise, efficient ventilation, and a wise distribution of hours, but it is also largely influenced by moral causes. Somnia quæ mentes ludunt volitantibus umbris, Nec delubra deum, nec ab æthere numina mittunt, Sed sibi quisque facit.