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. – Principal Doctrine 20
One of the many controversies in Epicurean philosophy has to do with whether the pleasures of the soul (or mental pleasures) are superior to those of the body, which is a doctrine that many attribute to Epicurus, perhaps to distance him from the earlier hedonism of the Cyrenaics, or perhaps to liken him a bit more to the Stoics or other philosophers who preach asceticism instead of hedonism.
I do not believe that Epicurus ever actually _said_ that mental pleasures are “superior” to those of the body: we see above in PD 20 that the mind does *not* shun pleasure. Period. But many Epicureans and non-Epicureans after him have come to the conclusion that they are superior. What Epicurus did say is that the pleasures (and pains) of the mind last longer than those of the body: we may hurt our bodies and be in pain for 10, or 30 minutes, or sometimes for longer in the cases of chronic disease, but these cases are rare. We may enjoy a meal, a drink, or sex, and those pleasures can last, but not for very long.
Mental pleasure and mental anxiety, on the other hand, can last a lifetime, or many years. We can also consciously reminisce, or anticipate, these pleasures–in fact, Epicurus advised this as a practice for abiding in pleasure. In this sense, the Epicurean distinguishes himself from the Cyrenaic, who only limited the opportunities for pleasure to that which was right in front of him in the here-and-now.
Diogenes of Oenoanda, in his Wall Inscription, elaborated on this: he argued first that it is difficult to compare the mental pains to bodily pains (Fragment 44), and later expressed that the soul is more powerful than the body (Fragment 48), and that “if we neglect the soul and only care for body (as Aristippus–the founder of the Cyrenaic school–advised) we’ll be deprived of the greatest pleasures“, which implies that he believed that the pleasures of the mind _are_ greater than those of the body.
In Fragment 106, Diogenes argues that it is natural for those in physical pain to express their pain, but that it is unnatural to complain for not being fully healthy. He is once again demonstrating the difference of physical versus mental pain, and how we have much more control of the mental state than the physical one.
Diogenes lived in the Second Century of Common Era, and had been fortunate enough to receive a centuries-long tradition of uninterrupted Epicurean discourse. One thing we can say with certainty is that, by the time the Wall was erected in Oenoanda, the Epicureans had been pondering these questions for many generations and had formed quite elaborate arguments on them.
In Fragment 45, Diogenes argues that the soul is greater and more powerful than the body (as PD 20 teaches) by the demonstration that we see in depressed people, who sometimes stop eating and self-inflict physical harm as a result of their chronic sadness: when the soul is in a state of great suffering, the body also suffers. He’s arguing that soul pains are bigger than bodily pains, but in some rare cases the opposite can also be true: bodily pains can be so intense and chronic that the mind is affected. In all cases, the training of the mind’s disposition so that it may abide in pleasure habitually is advised.
Consistent with what’s been said before, in Fragment 112 Diogenes states that the “sum of happiness is our disposition, of which we are masters”, by which he argues against choosing a career in military service–which produces dangers to our lives and health–or public speaking–which produces nervousness and insecurity. The idea is that we can more easily be self-sufficient in our pleasure if we retain our ability to control our mental disposition.