The problem of evil the Apologists solved by connecting it with a belief in the freedom of choice given spirits or angels who chose to depart from righteousness, and, thus becoming evil demons, have from the first beset man and still do beset him with temptations which cause him to sin. They regarded man, by virtue of his endowments of reason and of freedom of the will, as capable of immortal life or of complete death. The conditions of immortality were first, the maintenance of the knowledge of God and of his relation through the Logos to the created world, and secondly, persistence in a life aimed at moral perfection, a life which followed after the Spirit and did not yield to the bodily passions. In Tatian especially there is a distinct ascetic strain.[343] The best exposition of man’s moral obligations the Apologists believed to be found in the words of Jesus, but at the same time they agreed in holding that the essential element in a life of virtue was a clear knowledge of divine things through which man was at once raised above the things of this world into a pure and noble existence. Thus man was assured now of salvation, and in the future life was destined to enjoy immortality and the perfection of knowledge which would come with the direct vision of God.[344] But such a doctrine presupposes a revelation of God. This, as I have already pointed out, the Apologists said had been made in the beginning by the Logos who disclosed himself in the created universe and in man as a part thereof. Man, however, by yielding to sin, had lost that divine knowledge which had been his through the original revelation, with the result that repeated revelations had been necessary. The agents of these had been the inspired prophets of the Old Testament and to a slight degree the philosophers of Greece. The revelation of the Logos in Jesus Christ was simply an attestation and guarantee of the truths and predictions of the prophets, the highest stage in the history of revelation, confirming that revelation without changing its content in any way.