I am sure that I have made comments to the effect that Epicurus seemed to be saying that we should not pursue the pleasure of the moment, but pleasure measured over a lifetime.
I do not think that is exactly the right perspective either. Pleasure is not to be measured by time alone, as we clearly know from the letter to Menoeceus: "And even as men choose of food not merely and simply the larger portion, but the more pleasant, so the wise seek to enjoy the time which is most pleasant and not merely that which is longest."
This issue calls to mind why the wording of PD3 is so interesting. As translated by Bailey and most others, PD3 refers to "the limit of quantity in pleasures...." This is not a statement of "the best" pleasures or "the highest" pleasures or pleasures measured in any way other than "quantity." What is the meaning of "quantity" and how should we measure pleasure. if not by time?
Should we measure pleasure by "intensity"?
Is PD9's reference to "accumulation" a reference to "intensity"? PD 9. "If every pleasure had been capable of accumulation, not only over time but also over the entire body or at least over the principal parts of our nature, then pleasures would never differ from one another."
Should we measure pleasure by "purity" or "homogeneity" rather than by diverse composition?
18. Bodily pleasure does not increase when the pain of want has been removed; after that it only admits of variation. The limit of mental pleasure, however, is reached when we reflect on these bodily pleasures and their related emotions, which used to cause the mind the greatest alarms.
Should we measure pleasure by "reason"?
19. Unlimited time and limited time afford an equal amount of pleasure, if we measure the limits of that pleasure by reason.
Should we measure pleasure by whether it is physical or mental, giving one a greater weight than the other?
PD20 The flesh receives as unlimited the limits of pleasure; and to provide it requires unlimited time. But the mind, intellectually grasping what the end and limit of the flesh is, and banishing the terrors of the future, procures a complete and perfect life, and we have no longer any need of unlimited time. Nevertheless the mind does not shun pleasure, and even when circumstances make death imminent, the mind does not lack enjoyment of the best life.
Should we measure pleasure by whether it is natural or necessary?
29. Of our desires some are natural and necessary, others are natural but not necessary; and others are neither natural nor necessary, but are due to groundless opinion.
30. Those natural desires which entail no pain when unsatisfied, though pursued with an intense effort, are also due to groundless opinion; and it is not because of their own nature they are not got rid of but because of man's groundless opinions.
Here is at least one takeaway point that I think has to be concluded: ALL of the perspectives above are valid and are to be considered, but none of them standing alone answer the question of which choices and avoidances that everyone in every situation should make. Only the individual can make the determination of how he wants to evaluate his goal of pleasure in his own life. Whether he should choose a low-intensity pleasure over a long period, or high-intensity pleasure over a short period, is not a matter for which Nature lays out for everyone the same answer. Circumstances are going to differ by individual and by situation, and what course we should choose cannot be decided apart from the situations in which we find ourselves.
While we are certainly not going to choose only "the pleasures of the moment" it is equally unjustified by Nature to say that we should definitely choose "the total of pleasures over 75 years."