For a possession which is not diminished by being shared with others, if it is possessed and not shared, is not yet possessed as it ought to be possessed.

[Omnis enim res quae dando non deficit, dum habetur et non datur, nondum habetur quomodo habenda est.]

Augustine of Hippo (354-430) Christian church father, philosopher, saint [b. Aurelius Augustinus]

On Christian Doctrine [De Doctrina Christiana], Book 1, ch. 1 / § 1 (1.1.1) (AD 397) [tr. Shaw (1858)]
    (Source)

(Source (Latin)). Alternate translations:

Everything which does not decrease on being given away is not properly owned when it is owned and not given.
[tr. Robertson (1958)]

For everything which does not give out when given away is not yet possessed in the way in which it should be possessed, while it is possessed and not given away.
[tr. Green (1995)]

For if a thing is not diminished by being shared with others, it is not rightly owned if it is only owned and not shared.
[Example]