Full Idea
In the prehistory of anything that is now private property there was at least one moment at which something privately unowned was taken into private ownership.
Gist of Idea
Every thing which is now private started out as unowned
Source
G.A. Cohen (Are Freedom and Equality Compatible? [1986], 2)
Book Reference
'Contemporary Political Philosophy (2nd ed)', ed/tr. Goodin,RE/Pettit,P [Blackwell 2006], p.418
A Reaction
He is obviously talking about land and natural resources. Presumably a table which I made and own was always private property, although the land where the trees were grown was not. Though in some communities what I make could be automatically communal.