It was therefore natural that the Stoics, notwithstanding their own maxims, found themselves compelled to recognise differences among the bad and differences among the good. In reference to their system these differences were, indeed, made to depend in the case of the bad upon the greater or less difficulty of healing the moral defects, or, in the case of the good, upon qualities morally indifferent. [743] It was also natural that they should so nearly identify the state of προσκοπὴ—or progress towards wisdom, the only really existing state—with wisdom that it could hardly be distinguished therefrom. If there is a stage of progress at which a man is free from all emotions, discharges all his duties, knows all that is necessary, and is even secure against the danger of relapse, [744] such a stage cannot be distinguished from wisdom, either by its want of experience or by the absence of a clear knowledge of oneself. For has it not been frequently asserted that happiness is not increased by length of time, and that the wise man is at first not conscious of his wisdom? [745] If, however, the highest stage of approximation to wisdom is supposed still to fall short of wisdom, because it is not sure of its continuance, and though free from mental diseases, it is not free from emotions, [746] how, it may be asked, do these passing emotions differ from the mental affections which are found in the wise man? Is there any real distinction between them? If the progressing candidate has attained to freedom from diseased mental states, is the danger of a relapse very great? Besides, the Stoics were by no means agreed that the really wise man is free from all danger. Cleanthes held with the Cynics that virtue can never be lost; Chrysippus admitted that, in certain cases, it is defectible. [747] After all this admission is only one among many traits which prove that the Stoics were obliged to abate from the original severity of their demands. CHAPTER XII. APPLIED MORAL SCIENCE.