Lucius Caecilius Firmianus Lactantius

Immortality, then, is not the consequence of nature, but the reward and recompense of virtue. Lastly, man does not immediately upon his birth walk upright, but at first on all fours, because the nature of his body and of this present life is common to us with the dumb animals; afterwards, when his strength is confirmed, he raises himself, and his tongue is loosened so that he speaks plainly, and he ceases to be a dumb animal. And this argument teaches that man is born mortal; but that he afterwards becomes immortal, when he begins to live in conformity with the will of God, that is, to follow righteousness, which is comprised in the worship of God, since God raised man to a view of the heaven and of Himself. And this takes place when man, purified in the heavenly laver, lays aside his infancy together with all the pollution of his past life, and having received an increase of divine vigour, becomes a perfect and complete man.

Therefore, because God has set forth virtue before man, although the soul and the body are connected together, yet they are contrary, and oppose one another. The things which are good for the soul are evil to the body, that is, the avoiding of riches, the prohibiting of pleasures, the contempt of pain and death. In like manner, the things which are good for the body are evil to the soul, that is, desire and lust, by which riches are desired, and the enjoyments of various pleasures, by which the soul is weakened and destroyed.