From Augustine’s De Doctrina Christiana:
omnis enim res quae dando non deficit, dum habetur et non datur, nondum habetur quomodo habenda est.
For every thing which does not run out by being given, as long as it is held and not given, is no longer held in the way in which it ought to be.
Which reminds me of Aristotle’s litmus test for good habits and bad habits in the Ethics, but there is not time to go fishing for it right now.
Thanks, dear reader, should you ever find me, for giving that which increases with the giving.