 Given the huge problems that an account of haecceities seems to raise, it is worth seeing just why Scotus believes he needs to accept this view of individuation as opposed to a rival one. Scotus defends haecceities by rejecting all alternative theories of individuation known to him. Rejecting qualitative theories is easy for the scholastics. Suppose that all things of a given kind in some sense share the same nature. The nature as such cannot explain individuation. So the explanation must be somehow non-essential. But non-essential qualitative or accidental features of a thing are posterior to the thing itself, since although the substance must have some accidental features, precisely which ones it has is a matter of historical chance (Scotus, Ordinatio II, d. 3, p. 1, q. 4, n. 87 (Scotus [OO], 7:432–433; Spade (1994), 79)). Things are not identical with their life-stories (on this, see Cross [1999b]). Indeed, Scotus goes so far as to suggest that the accidents of a substance – at least, its quantities, qualities, and relations – are individuated by their own haecceities, something that is not often spotted in the commentaries (on this, see Scotus, Ordinatio II, d. 3, p. 1, q. 4, n. 89 (Scotus [OO], 7:434; Spade (1994), 79–80)). The great 17th century Scotist, John Poncius, extends this claim to cover even so-called propria, necessary but non-defining properties: paradigmatically, a capacity to smile in human beings (see Poncius, Disputatio Metaphysica VI, q. 9 [Poncius (1659), 138b]).