As a general conclusion, it is proposed that animals and humans rank priorities in choice situations and thus optimize their behavior by the amount of pleasure aroused by this behavior. Bentham's fourteen tables of the springs of action, and Duncker's four causes of pleasure can be compared to one another for the very good reason that present or expected pleasure is the common currency to past, present, and future actions. At the same time pleasure renders unnecessary high levels of rationality in the process of decision making. In situations of conflicting motivations, pleasure would serve as a common currency, with additive properties, for the ranking of priorities and the resulting tradeoffs. The great advantage of pleasure both as a motivation and as a key to optimization lies in its versatility.
Pleasure opens an infinite register of new responses.
Indeed it is far more simple to maximize pleasure than to accumulate within the CNS an infinite number of instinctual responses. Pleasure in this case is analogous to the multiplicative function programmed in a calculator. It is far more simple to have access to that function than to store the infinite number of possible multiplications of rational numbers. Actually it is to be understood as the freedom to choose one's own way to maximize pleasure.