8 R. Define therefore the True. A. That is true which is so as it appears to the knower, if he will and can know. R. That therefore will not be true which no one can know? Then, if that is false which seems otherwise than it is; how if to one this stone should seem a stone, to another wood? will the same thing be both false and true? A. That former position disturbs me more, how, if anything cannot be known, it results from that that it is not true.
For as to this, that one thing is both true and false, I do not much care. For I see one thing, compared with diverse things, to be both greater and smaller. From which it results, that nothing is more or less of itself. For these are terms of comparison. R. But if you say that nothing is true of itself, do you not fear the inference, that nothing is of itself? For whereby this is wood, thereby is it also true wood. Nor can it be, that of itself, that is, without a knower, it should be wood, and should not be true wood. A. Therefore thus I say and so I define, nor do I fear lest my definition be disapproved on the ground of excessive brevity: for to me that seems to be true which is. R. Nothing then will be false, because whatever is, is true. A. You have driven me into close straits, and I am wholly unprovided of an answer.
So it comes to pass that whereas I am unwilling to be taught except by these questionings, I fear now to be questioned.
Source: Soliloquies (New Advent)