Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
a man who breathes is alive, and a man who is alive breathes. Some again cannot be reversed: because he who walks moves it does not follow that he who moves walks.
So too a woman, who has not been delivered of a child, may have had intercourse with a man, there may be waves without a high wind, and a man may die without having received a wound in the heart. Similarly seed may be sown without a harvest resulting, a man, who was never at Athens, may
There are other indications or εἰκότα, that is probabilities, as the Greeks call them, which do not involve a necessary conclusion. These may not be sufficient in themselves to remove doubt, but may yet be of the greatest value when taken in conjunction with other indications.
The Latin equivalent of the Greek σημεῖον is signum, a sign, though some have called it indicium, an indication, or vestigium, a trace. Such signs or indications enable us to infer that something else has happened; blood for instance may lead us to infer that a murder has taken place. But bloodstains on a garment may be the result of the slaying of a victim at a sacrifice or of bleeding at the nose. Everyone who has a bloodstain on his clothes is not necessarily a murderer.
But although such an indication may not amount to proof in itself, yet it may be produced as evidence in conjunction with other indications, such for instance as the fact that the man with the bloodstain was the enemy of the murdered man, had threatened him previously or was in the same place with him. Add the indication in question to these, and what was previously only a suspicion may become a certainty.