It results from their periodicity that, in men of genius, sterile years precede productive years, these again to be followed by sterility, the barren periods being marked by psychological self-depreciation, by the feeling that they are less than other men; times in which the remembrance of the creative periods is a torment, and when they envy those who go about undisturbed by such penalties. Just as his moments of ecstasy are more poignant, so are the periods of depression of a man of genius more intense than those of other men. Every great man has such periods, of longer or shorter duration, times in which he loses self-confidence, in which he thinks of suicide; times in which, indeed, he may be sowing the seeds of a future harvest, but which are devoid of the stimulus to production; times which call forth the blind criticisms 'How such a genius is degenerating!' 'How he has played himself out!' 'How he repeates himself!' and so forth.