"'Does philosophy, then, make happiness?' said he, interrupting. 'Assuredly,' said I, 'and it alone.' 'What, then, is philosophy?' he said, 'and what is happiness? Pray tell me, unless something hinders you from saying.' "'Philosophy,' said I, 'is a knowledge of that which really exists and a clear perception of truth, and happiness is the reward of such knowledge and wisdom.' 'But what do you call God?' said he. 'That which always maintains the same nature and is the cause of all other things--that, indeed, is God.' So I answered him, and he listened with pleasure." The conversation, which is too long to be fully transcribed, turns on the attributes of the soul. Justin discourses on that topic after the manner of the Platonists. The old man, on the other hand, urges him to study the prophets of the Old Testament, for they predicted the coming of Christ, and their prophecies have been fulfilled. "'They,' said he, 'both glorified the Creator, the God and Father of all, and proclaimed his Son the Christ sent by him. But,' he added, 'pray that, above all things, the gates of light may be opened to you, for these things cannot be perceived or understood by all, but only by him to whom God and his Christ have imparted wisdom.' "When he had spoken these and many other things which there is no time for mentioning at present, he went away, bidding me attend to them, and I have not seen him since. But straightway a flame was kindled in my soul, and a love of the prophets and of those men who are friends of Christ possessed me; and whilst revolving his words in my mind I found this philosophy alone to be safe and profitable. Thus and for this reason I am a philosopher. Moreover, I would that all, making a resolution similar to my own, would regard the words of the Saviour, for they possess a terrible power in themselves, and are sufficient to inspire those who turn aside from the path of rectitude with awe, while the sweetest rest is afforded to those who diligently observe them." The _Dialogue_ from which these passages are taken is a real or imaginary disputation with Trypho, a learned Jew at Ephesus, respecting the principles of Christianity, and contains an elaborate demonstration that Christ is the Messiah of the Old Testament. The controversy is carried on with courtesy on both sides, and each disputant is equally earnest in his attempt to convert the other. Justin was a very copious writer. The two most important of his writings now remaining are the two _Apologies_. These are certainly the two earliest of the numerous ancient pleas for toleration of Christianity now extant. The first _Apologia_ is addressed to the emperor Antoninus Pius and the Roman senate and the "whole people of the Romans"; and the purport of it may be inferred from the commencement, in which Justin says that he presents this "address and petition in behalf of all nations who are unjustly hated and wantonly abused, myself being one of them."