He asserts, moreover, that supposing angels and men to have a proper voluntary agency, to be endued with reason and the power of examining and deciding upon examination, they must, in the very nature of things, be capable of transgressing; and that, indeed, otherwise excellence would not have been either pleasant or an object of desire, because they would not have known its value, neither would it have been capable of reward, or of being enjoyed when attained; nor would intercourse with God have been valued, because it would have come without any impulse, choice, care, or endeavour of their own(251). This is the only approach to a solution of the difficulty which all the study of philosophers and divines has ever discovered. But when we come to inquire why some of God’s creatures transgressed, and some continued in obedience, this, he says, is a mystery which God has reserved to himself, and which it is presumption for us to inquire into; and that we ought to consider what it has pleased him to reveal as a favour, and leave to him that which he has not thought proper to make known(252). He notwithstanding suggests this practical good arising out of the existence of evil, that the love of God will be more earnestly cherished for ever by those who have known by experience the evil of sin, and have obtained their deliverance from it not without their own exertion; and therefore that this may be regarded as a reason why God permitted evil(253). The sobriety of these views is so obvious, that it appears unnecessary to dwell further upon them. CHAPTER VI. THE EVIL SPIRITS. Although Irenæus does not think proper to discuss the subject of the origin of evil, properly so called, he speaks agreeably to the Scriptures as to its introduction into this lower world, and in some degree fills up their outline. Thus he describes Satan as having been originally one of the angels who had power over the air(254). He attributes the beginning of his overt acts of rebellion to his envy towards man(255), because he had been made in the image of God, i. e. immortal(256); whom through envy he stirred up to rebellion likewise(257), and that by falsehood(258), putting on the form of the serpent, that he might escape the eye of God(259): wherefore, although God had pity upon man, as having fallen through weakness(260), and because otherwise Satan would have frustrated the Divine purpose(261), he totally cut off from himself the apostate angels(262), and doomed them and their Prince to the eternal fire(263), which he had from the beginning prepared for obstinate transgressors(264), although he did not make known to them at that time that their lot was irremediable(265). The next act of the apostate spirits was to mingle themselves with human nature by carnal copulation with women, and thus to cause the total corruption of the old world and its inhabitants (notwithstanding the preaching of Enoch to these fallen spirits), and consequently their destruction(266).