"I need not, like Labio, coin a term from the Greek," said Afer, "to describe my system. I am a materialist. I believe nothing save what my senses attest. They show me neither God nor soul; and I am determined never to accept any other criterion."
"Are you quite sure," asked Dionysius, "that you are thus determined? I should like to shake such a determination."
"You'll fail," replied Afer, smiling. "Which of your senses, then, has attested to you that very determination? Can you see, taste, smell, hear, or touch it? And yet you tell us you are sure of it. If so, you can believe in, and be sure of, something which has never been submitted to the criterion which alone you admit."
"A determination is not a thing," said Afer hastily, and with a little confusion.
"Was Julius Cæsar a thing?" persisted Dionysius; "because if you believe that Julius Cæsar existed, having heard of him and read of him, your senses of hearing and seeing do not attest to you in this case the existence of Julius Cæsar, but simply the affirmations of others that he has existed. My hearing attests to me that Strabo says he has been in Spain; and this, if there were no other reason, would satisfy me that Spain exists; yet it is Strabo whom I hear. I do not hear Spain."
Augustus clapped his hands gently, and laughed. Domitius Afer, with visible anger, exclaimed,
"I mean, that I will take nothing but upon proof. Prove that the soul is immortal; prove that one supreme God exists. Every thing which a reasonable man believes ought to be demonstrated."
"I hope," said Dionysius, "to prove those two truths to your satisfaction. But as you say that all we believe ought to be demonstrated, I will first offer you a demonstration, that it is impossible to demonstrate every thing. To prove any proposition, you require a second; and to prove the second, in its turn, you require a third; and it is upon this third, if you admit it, that the demonstration of the first depends. But if you had fifty propositions, or any number, in the chain, what proves the last of them?"
"Another yet," said Afer.
"But," said the Greek, "either you come to a last, or you never come to a last. If you never come to a last proposition, you never finish your proof; you leave it uncompleted; it remains still no proof at all; you have not performed what you undertook. And if you do come to a final proposition, which is supported by no other, what supports it?"