LET. V U .] TO NEBBIDIUS. 15 doubt, the m ind received more reliable and correct impressions before it was involved in the illusions which the senses produce, it follows that w e m ust attribute greater value to the impres­ sions of men asleep than o f men awake, and of m en insane than hf those who are free from such m ental disorder: for th ey are, in these states of inind, impressed by the saine kind of images as impressed them before they were indebted for information to these m ost deceptive messengers, the sen ses; and thus, either the sun which they see m ust be more real than the sun which is seen by m en in their soimd judgm ent and in their waking hom’ s, or that which is an illusion m ust be better than what is real But if these conclusions, m y dear Nebridius, are, as they obviously are, w holly absurd, it is demonstrated that the image of which you speak is nothing else than a blow inflicted by the senses, the function o f which in connection w ith these images is not, as you w rite, the mere suggestion or admoni­ tion occasioning their formation by the m ind w ithin itseK, but the actual bringing in to the m ind, or, to speak more definitely, impressing upon it of the illusions to which through the senses w e are subject. The difficulty w hich you feel as to the ques­ tion how it comes to pass that w e Can conceive in thought, faces and forms w hich w e have never seen, is one w hich proves the acuteness o f your mind. I shall therefore do what m ay extend th is letter beyond the usual len g th ; not, however, beyond the length which you w ill approve, for I believe that the greater the fulness w ith which I write to you, the more welcome shall m y letter be. 4. I perceive that all those im ages w hich yon as w ell as many others call pJiantasice, may be m ost conveniently and accurately divided into three classes, according as they origi­ nate w ith the senses, or th e imagination, or the faculty of rea­ son, Exam ples of the first class are when the mind forms w ithin itse lf and presents to me the image of your face, or of Carthage, or of our departed friend Verecundus, or of any other thing at present or formerly existing, w hich I have m yself seen and perceived. Under the second class come a ll th in gs which we imagine to have been, or to he so and s o : e.g. when, for the sake o f illustration in discourse, w e ourselves suppose things which have no existence, but which lire not prejudicial to