In X.1-5 Aristotle revisits the topic of pleasure, reiterating some of the points he made in VII.11-14 (e.g., that every activity has its own inherent pleasure) but also extending them in several ways.
Aristotle presents evidence indicating that the enjoyment of an activity completes [τελειοῖ / teleioi] that activity. When we perceive with the senses or conceive with the mind, we are most completely active or "at work" if we are engaged with the most beautiful [καλός / kalos] and serious [σπουδαῖος / spoudaios] objects of awareness. The reason seems to be that we enjoy both the active being of what we perceive/conceive (say, the aliveness of a bird in flight) and our own active awareness of what we perceive/conceive. Although Aristotle doesn't put it quite this way, we could say that enjoyment is a form of awareness: it consists in awareness of the world and (since, as we saw in IX.9-12, for human beings living simply is perceiving and thinking) awareness of our own aliveness.
Furthermore, because pleasures are bound up with the activities they complete, they in turn are brought to completion in ways that correspond to the activities: the inherent [οἰκείος / oikeios] pleasures of sight differ from those of hearing or taste or touch, the pleasures of the mind differ from those of the senses, there are various pleasures of the mind (e.g., recollecting, imagining, hoping, learning, contemplating), etc. Thus pleasures are not interchangeable but deserve to be valued and pursued in ways that do justice to the nature of the underlying activities.
Based on these factors, Aristotle argues that the most complete activity is the most enjoyable: for instance, it's more pleasurable to deeply understand a significant concept than to become acquainted with a trivial fact, or to witness a seriously worthy person performing a beautifully right action than to witness a worthless, morally corrupt person performing a repulsively ugly action. Naturally, there are many kinds of corruption and damage that human beings can experience, but corrupt/damaged people and their feelings and pleasures are not the standard of value in human life. Instead, the measure [κανόν / kanon] of what is truly enjoyable is the kind of person who is completely developed, mature, serious, worthy, good, beautifully right, wise, sagacious, fulfilled, etc.
These considerations lead up to Aristotle's final integrations in the remainder of Book X.
(Cross-posted at philosopher.coach.)
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