And further, the analysis of volition involved in the argument seems to be insufficient. For there are other springs of action to be taken account of than pleasure and its opposite. Habit, imitation, and interests of a more comprehensive kind than desire of pleasant feeling, are all motives to action. It is true that pleasure is always felt in the successful performance of an action, and it is also true that the inhibition of will is always painful; but it is none the less incorrect to look either upon the pleasure that follows from the action, or the pain that would be the result of its inhibition as, in ordinary cases, the motive. It is motives of a different kind than pleasure, such as imitation[167] and the influence of ideal ends, which most often lead to progress. And the progress that is due to such motives cannot be measured by its effect in increasing pleasure, nor assumed to make pleasure and life correspond. Other activities less advantageous in nature in all respects but this, might, so far as the reasoning goes, lead to equal or to more pleasurable consequences. At the best, therefore, the above argument only proves a general tendency towards the coincidence of pleasurable actions with actions which promote life; it does not show that the increase of life can be accurately measured by pleasure. The process of natural selection might kill off all organisms whose desires led them normally to action hurtful to life. But sufficient evidence has not been brought forward to show that it is fitted to produce an exact proportion between progress and pleasure. [Sidenote: (β) The pessimist doctrine that life tends to misery:] [Sidenote: (_aa_) the hypothesis of the unconscious;]