The most widespread fellowship existing among men is that of all with all others. Here we must preserve the communal sharing of all the things that nature brings forth for the common use of mankind, in such a way that whatever is assigned by statutes and civil law should remain in such possession as those laws may have laid down, but the rest should be regarded as the Greek proverb has it: everything is common among friends. The things that are common to all men seem to be of the kind that Ennius defines in one case, from which we can extrapolate to many cases:
A man who kindly shows the path to someone who is
lost lights another’s light, so to speak, from his own.
For his own shines no less because he has lit another’s.
With this one instance, he advises us that if any assistance can be provided without detriment to oneself, it should be given even to a stranger. Therefore such things as the following are to be shared: One should not keep others from fresh water, should allow them to take fire from your fire, should give trustworthy counsel to someone who is seeking advice; for they are useful to those who receive them and cause no trouble to the giver. Since, though, the resources of the individuals are small, but the mass of those who are in need is infinitely great, general liberality must be measured according to the limit laid down by Ennius, that his own light shine no less; then we shall still be capable of being liberal to those close to us.
-Cicero, De Officiis, Book I, 53