Desire is an insight into the nature of matter; joy or pleasure into the nature of form.
What Diotema calls love in Symposium is desire, as (1) a reality that strives (2) to fill an emptiness. As the former it is born of fulness, as the latter born of poverty. Matter is not privation, for it belongs to being, but it belongs to being as striving for it.
Considered without form, matter is irrational; but is rational as ordered to form.
If we abstract matter from all form it becomes properly unintelligible, but we can abstract in another sense, where we see matter as ordered to the “totality” of forms it could have, and so arising from no first and stopping at no last. So taken, we get the infinite in the familiar, quantitative sense. This abstraction defines space and time. Taken concretely, however, spacetime is the domain of desire for being.
Form is being simply, so form is other than space or time. Though some forms express themselves only through matter, and to the extent that they do have an accidental modification to their enjoyment, form and enjoyment as such are goals of the desire for being, and so are properly above space and time. Even where form is temporal, time hangs from it, like the cables and deck of the suspension bridge hang from the pylons and towers. I get what someone means when he speaks of forms in spacetime, but it would be better to see spacetime as suspended and hanging from form.
Just Thomism 