Spinoza, whose philosophy of being-in-the-world includes concepts of joy and sorrow which contribute to or detract from our quality of engagement in the world– outlines two types of joy which are useful to consider. One type is partial, and the other is more of an overarching condition which has the potential to lead to creative fulfilment, purpose, and an ability to act in the world. Titillatio (pleasurable excitement) is only in partial relationship to the organism as a whole. Affecting only a “sub-group of parts of the body,” its interaction is incomplete, and thus deserves cautious attention, because it listens to partial signals, not fully-encompassing ones. It is inattentive to broader details, to other factors in the contexts of its own fulfilment, and can indeed lead to exhaustion (both of an individual, and of the larger cohort to which that individual belongs). Spinoza mentions love of money, sexual fulfilment, and ambition in this category.

The condition of hilaritas, or cheerfulness, however, reflects on the idea of a body as an ecology, both unto itself, and in relation to others. This “joy” is one which calls on the body or self as a whole, affecting “not only a subgroup of functions of the organism, but each and every one,” and therefore its totality. (Arne Naess, Deep Ecology for the 21th Century, 1973; p.252.) This has the potential to be complete in its integration of our knowledge-of-the-world. It is a condition to which one can aspire (approaching what he calls “perfection”) which makes for the circumstances of fulfilment of action, of complex thought, and of making decisions which can be in fuller relationship with more of the world, and with the possibility of a better-functioning world as a result.

Hilaritas is thus a condition which includes a kind of expansion and progression of sensibility and relationship, because it can accommodate more. There is always something more to know, incorporate or acknowledge. This, for Spinoza, brings forth improvement. But one might ask, where does this “more,” this improvement, open out from?

from “Hungry Ghosts.” Full text available in link