Lactantius

“ But fire is both without perception and is seen, and burns when touched. But the soul is both endowed with perception and cannot be seen, and does not burn. From which it is evident that the soul is something like God. But they who suppose that it is wind are deceived by this, because we appear to live by drawing breath from the air. Varro gives this definition: “The soul is air conceived in the mouth, warmed in the lungs, heated in the heart, diffused into the body.” ”

“ It remains to speak of the soul, although its system and nature cannot be perceived. Nor, therefore, do we fail to understand that the soul is immortal, since whatever is vigorous and is in motion by itself at all times, and cannot be seen or touched, must he eternal. But what the soul is, is not yet agreed upon by philosophers, and perhaps will never be agreed upon. ”

“ For if the soul appears to be extinguished when the blood is poured forth through a wound, or is exhausted by the heat of fevers, it does not therefore follow that the system of the soul is to be placed in the material of the blood ”