Cicero, Tusc. Disp 1.30
“Moreover, this seems to be the strongest point to offer on why we believe that there are gods—the fact there are no people so savage, no one in the world so bestial, that no thought of the gods touches his mind. While it is true that many people believe silly things about the gods—which customarily happens because of corrupted customs—still all people believe in divine power and divine nature. Furthermore, human conferences and consensus do not create this, nor is the idea affirmed by practices or laws, but in every matter the shared belief of all peoples must be considered a natural law.
Is there anyone who does not mourn the death of their loved ones because he believes that they have been deprived of life’s pleasures? Remove this belief and you will remove mourning. No one mourns for their own discomfort. People do feel pain, but the mourning and tears of sorrow come from that fact that we believe that a person whom we love has lost access to life’s pleasures and are aware of this. We are led by nature to believe this, not by any teaching or act of reason.”
Ut porro firmissimum hoc adferri videtur, cur deos esse credamus, quod nulla gens tam fera, nemo omnium tam est immanis, cuius mentem non imbuerit deorum opinio—multi de dis prava sentiunt, id enim vitioso more effici solet, omnes tamen esse vim et naturam divinam arbitrantur, nec vero id collocutio hominum aut consensus effecit, non institutis opinio est confirmata, non legibus, omni autem in re consensio omnium gentium lex naturae putanda est—quis est igitur qui suorum mortem primum non eo lugeat, quod eos orbatos vitae commodis arbitretur? Tolle hanc opinionem, luctum sustuleris. Nemo enim maeret suo incommodo: dolent fortasse et anguntur: sed illa lugubris lamentatio fletusque maerens ex eo est, quod eum, quem dileximus, vitae commodis privatum arbitramur idque sentire. Atque haec ita sentimus natura duce, nulla ratione nullaque doctrina.