[Original Latin Title: De Divinatione]
When, therefore, the soul has been withdrawn by sleep from contact with sensual ties, then does it recall the past, comprehend the present, and foresee the future. For though the sleeping body then lies as if it were dead, yet the soul is alive and strong, and will be much more so after death when it is wholly free of the body. Hence its power to divine is much enhanced by the approach of death. For example, those in the grasp of a serious and fatal sickness realize the fact that death impends; and so, visions of dead men generally appear to them and then their desire for fame is strongest; while those who have lived otherwise than as they should, feel, at such a time, the keenest sorrow for their sins.
The human soul is in some degree derived and drawn from a source exterior to itself. Hence we understand that outside the human soul there is a divine soul from which the human soul is sprung. Moreover, that portion of the human soul which is endowed with sensation, motion, and carnal desire is inseparable from bodily influence; while that portion which thinks and reasons is most vigorous when it is most distant from the body.
The soul is of such a force and nature that, when we are awake, it is active, not because of any extraneous impulse, but because of its own inherent power of self-motion and a certain incredible swiftness. When the soul is supported by the bodily members and by the five senses its powers of perception, thought, and apprehension are more trustworthy. But when these physical aids are removed and the body is inert in sleep, the soul then moves of itself. And so, in that state, visions flit about it, actions occur and it seems to hear and say many things.
Power of Divination
Though without eyes it is impossible to perform the act and function of sight, and though the eyes sometimes cannot perform their appointed function, yet when a person has even once so employed his eyes as to see things as they are, he has a realization of what correct vision is. Likewise, therefore, although without the power of divination it is impossible for the act and function of divining to exist, and though one with that power may sometimes be mistaken and may make erroneous prophecies, yet it is enough to establish the existence of divination that a single event has been so clearly foretold as to exclude the hypothesis of chance. But there are many such instances; therefore, the existence of divination must be conceded.
As in judicial causes the prosecutor draws one inference and the lawyer for the defendant another from the same set of facts, and yet the inferences of both are plausible; so, in all investigations in which it is customary to employ conjecture, ambiguity is found.