33 R. What need is there any longer than that we should inquire concerning the science of disputation? For whether the figures of Geometry are in the Truth, or the Truth is in them, that they are contained in our soul, that, is, in our intelligence, no one calls in question, and through this fact Truth also is compelled to be in our mind. But if every science whatever is so in the mind, as in the subject inseparably, and if Truth is not able to perish; why, I ask, do we doubt concerning the perpetual life of the mind through I know not what familiarity with death?
Or have that line or squareness or roundness other things which they imitate that they may be true? A. In no way can I believe that, unless perchance a line be something else than length without breadth, and a circle something else than a circumscribed line everywhere verging equally to the centre. Why then do we hesitate? Or is not Truth where these things are? A. God avert such madness. R. Or is not the science in the mind? A. Who would say that? R. But is it possible, the subject perishing, that that which is in the subject should perdure? A. When could I imagine such a thing? R. It remains to suppose that Truth may fail. A. Whence could this be brought to pass? R. Therefore the soul is immortal: now at last yield to your own arguments, believe the Truth; she cries out that she dwells in you, and is immortal, and that her seat cannot be withdrawn from her by any possible death of the body.
Turn away from your shadow, return into yourself; of no meaning is the destruction you fear, except that you have forgotten that you can not be destroyed. A. I hear, I come to a better mind, I begin to recollect myself. But I beg you would expedite those things which remain; how, in an undisciplined mind, for a mortal one we cannot call it, Science and Truth are to be understood to be. R. That question requires another volume, if you would have it treated thoroughly: moreover also I see occasion for you to review those things, which, after our best power, have been already examined; because if no one of those things which have been admitted is doubtful, I think that we have accomplished much, and with no small security may proceed to push our inquiries farther.
Source: Soliloquies (New Advent)