A third species of evidence, which is of the highest importance in this case, is the belief which the writers of these times had, that the prophecy of Isaiah, which stated, that men should turn their swords into ploughshares, and their spears into pruning-hooks, was then in the act of completion. Irenaeus, who flourished about the year 180, affirms, that this famous prophecy had been completed in his time; "for the Christians, says he, have changed their swords and their lances into instruments of peace, and they know not how to fight," Justin Martyr, who was cotemporary with Irenaeus, asserted the same thing, which he could not have done if the Christians in his time had engaged in war. "That the prophecy, says he, is fulfilled, you have good reason to believe, for we, who in times past killed one another, do not now fight with our enemies." And here it is observable, that the word "fight" does not mean to strike, or to beat, or to give a blow, but to fight as in war; and the word "enemy" does not mean a common adversary, or one who has injured us, but an enemy of the state; and the sentence, which follows that which has been given, puts the matter again out of all doubt. Tertullian, who lived after these, speaks in those remarkable words: "Deny that these (meaning the turning of swords into ploughshares) are the things prophesied of, when you see what you see, or that they are the things fulfilled, when you read what you read; but if you deny neither of these positions, then you must confess, that the prophecy has been accomplished, as far as the practice of every individual is concerned, to whom it is applicable." I might go from Tertullian even as far as Theoderet, if it were necessary, to shew, that the prophecy in question was considered as in the act of completion in those times. The fourth and last proof will be found in the assertions of Celsus, and in the reply of Origen to that writer. Celsus, who lived at the end of the second century, attacked the Christian religion. He made it one of his charges against the Christians, that they refused in his time to bear arms for the emperor, even in the case of necessity, and when their services would have been accepted. He told them farther, that if the rest of the empire were of their opinion, it would soon be overrun by the Barbarians. Now Celsus dared not have brought this charge against the Christians, if the fact had not been publicly known. But let us see whether it was denied by those, who were of opinion that his work demanded a reply. The person, who wrote against him in favour of Christianity, was Origen, who lived in the third century. But Origen, in his answer, admits the fact as stated by Celsus, that the Christians would not bear arms, and justifies them for refusing the practice on the principle of the unlawfulness of war.