The former theory[179] might be put forward as indicating how it is possible to institute a connection between pleasure and evolution. But it has been already shown that neither the actual facts of life, nor the tendencies to action, can be so interpreted as to make their nature and development correspond, with any degree of exactness, with pleasure and its increase.[180] Nor is it possible to make out that every pain corresponds to a loss of vitality, every pleasure heightens it. On the contrary, the assertion that pleasure-giving actions and life-preserving actions coincide, is due to a hasty generalisation which cannot include all the facts. That it holds throughout a considerable extent is true. Pleasure is, at any rate, a usual accompaniment of the normal processes of the development of life; and pain reaches its climax in death. But yet there is a broad margin of experience for which the generalisation is incorrect. There are numerous cases of painful and pleasurable sensations which cannot be shown to be, respectively, destructive of, and beneficial to, vitality. As Mr Bain, who always keeps the facts in view, admits, with regard to the feelings connected with the five senses, "we cannot contend that the degree of augmented vital energy corresponds always with the degree of the pleasure."[181] The same discrepancy may be observed in more complex experiences. The effort after a fuller life, whether physical or mental, even when its ultimate success is not doubtful, may bring more pain than pleasure; while the life which never strains its powers towards the limits of endurance, may experience almost uninterrupted pleasure: but such pleasure is the sure herald of the process of degeneration. [Sidenote: (β) may be held to depend on medium or normal functioning.]