Full Idea
If it does not at present exist, or, if it has not existed in the past, or if it is not going to exist in the future, it will not be a property [idion] at all.
Clarification
'Idion' is a strictly individual property
Gist of Idea
An individual property has to exist (in past, present or future)
Source
Aristotle (Topics [c.331 BCE], 129a27)
Book Reference
Aristotle: 'Posterior Analytics and Topica', ed/tr. Tredennick,H/Forster,ES [Harvard 1960], p.485
A Reaction
This seems to cramp our style in counterfactual discussion. Can't we even mention an individual property if we believe that it will never exist. Utopian political discussion will have to cease!