Whether it is lawful for a man to possess a thing as his own?

Objections

Objection 1 : It would seem unlawful for a man to possess a thing as his own. For whatever is contrary to the natural law is unlawful. Now according to the natural law all things are common property: and the possession of property is contrary to this community of goods. Therefore it is unlawful for any man to appropriate any external thing to himself.
Objection 2 : Further, Basil in expounding the words of the rich man quoted above (Article [1], Objection [2]), says: "The rich who deem as their own property the common goods they have seized upon, are like to those who by going beforehand to the play prevent others from coming, and appropriate to themselves what is intended for common use." Now it would be unlawful to prevent others from obtaining possession of common goods. Therefore it is unlawful to appropriate to oneself what belongs to the community.
Objection 3 : Further, Ambrose says [*Serm. lxiv, de temp.], and his words are quoted in the Decretals [*Dist. xlvii., Can. Sicut hi.]: "Let no man call his own that which is common property": and by "common" he means external things, as is clear from the context. Therefore it seems unlawful for a man to appropriate an external thing to himself.