17. A. Proceed, I pray; for now perchance thou hast begun to teach concerning falsities not falsely: but now I am considering of what sort that class of falsities may be, of which thou hast said, It tends to be, and is not. R. Why should you not consider? They are the same things, which already we have largely passed review. Does not thy image in the mirror appear to will to be thou thyself, but to be therefore false, because it is not? A. This does, in very deed, seem so. R. And as to pictures, and all such expressed resemblances, every such thing wrought by the artist? Do they not press to be that, after whose similitude they have been made? A. I must certainly own this to be true. R. And you will allow, I believe, that the deceits under which dreamers, or madmen suffer, are to be included in this kind. A. None more: for none tend more to be such things as the waking and the sane discern; and yet they are hereby false, because that which they tend to be they cannot be. R. Why need I now say more concerning the gliding towers, or the dipped oar, or the shadows of bodies? It is plain, as I think, that they are to be measured by this rule. A. Most evidently they are. R. I say nothing concerning the remaining senses; for no one by consideration will fail to find this, that in the various things which are subject to our sense, that is called false which tends to be anything and is not.

17. A. Perge, quaeso; nunc enim fortasse de falsis non falsa docere coepisti: sed jam illud genus exspecto quale sit quod dixisti, esse tendit et non est. R. Quidni exspectes? Eadem illa sunt, quorum multa supra memoravimus. Annon tibi videtur imago tua de speculo quasi tu ipse velle esse, sed ideo esse falsa, quod non est? A. Valde hoc videtur. R. Quid omnis pictura vel cujuscemodi simulacrum, et id genus omnia opificum? nonne illud esse contendunt, ad cujus quidque similitudinem factum est? A. Prorsus adducor. R. Jam ea quibus vel dormientes vel furentes falluntur, concedis, ut opinor, in eo esse genere. A. Et nulla 0893 magis: nam nulla magis tendunt talia esse, qualia vel vigilantes vel sani cernunt; et eo tamen falsa sunt, quo id quod tendunt esse non possunt. R. Quid jam de turrium motu, vel de merso remo, vel de umbris corporum plura dicam? Planum est, ut arbitror, ex hac regula esse metienda. A. Planissimum. R. Taceo de caeteris sensibus; nam nemo considerans non hoc inveniet, falsum appellari in rebus ipsis quas sentimus, quod esse aliquid tendit et non est.