Like intention and purpose desire is another term that can't be flattened out. It's no arrow, it's at an impossible angle. And so there can't be a calculus of desire, or desiring machines, except as catchy titles. So, there's no self without the disequilibrium of desire, and no desire without a body, and no body without matter or mattering. Looked at straight on you are sure it was an illusion, but then it doesn't fade on exposure but grows perversely stronger, like enchantment without a sorcerer. Of course it differs from its civilised cousins, intention and purpose, because it rides you, giving birth to you again and again, in ever more indiscreet forms. It comes at you from the side, from a sacred blind-spot in will, and you don't easily step into it. It is fresher than you are and if you take it on it comes over with a jolt, 'Ah, ...ah!', like suddenly jumping into cold water. Not a warm bath at all, that's reserved for the desireless state, something you can only get to by satisfying it.