13 R. Now give heed, while we run over the same things once more, that what we are endeavoring to show may come more plainly to view. A. Lo, here I am, speak what you will. For I have once for all resolved to endure this circuitous course, nor will I be wearied out in it, hoping so ardently to arrive at length whither I perceive that we are tending. R. You do well. But take note whether it seems to you, when we see a resemblance in eggs, that we can justly say that any one of them is false. A. Far from it.
For if all are eggs, they are true eggs. R. And when we see an image reflected from a mirror, by what signs do we apprehend it to be false? A. By the fact that it cannot be grasped, gives forth no sound, does not move independently, does not live, and by innumerable other properties, which it were tedious to detail. R. I see you are averse to delay, and regard must be borne to your haste. Then, not to recall every particular, if those men also whom we see in dreams, were able to live, speak, be grasped by waking men, and there were no difference between them and those whom when awake and sane we address and see, should we then have any reason to call them false? A. What possible right could we have to do so? R. Therefore if they were true, in exact proportion as they were likest the truth, and as no difference existed between them and the true and false so far as they were, by those or other differences, convicted of being dissimilar; must it not be confessed that similitude is the mother of truth, and dissimilitude of falsehood? A. I have no answer to make, and I am ashamed of my former so hasty assent.
Source: Soliloquies (New Advent)