IV. 4. 14
(Armstrong Selection and Translation from the Enneads)
As for the bodies which are said to be produced by Nature, the elements are just precisely products of Nature: but are animals and plants so disposed as to have Nature present in them? Their relationship to Nature is like that of air to light; when light goes away air holds nothing of it, light is separate from air and air from light, and they do not mingle. Or it is like that of fire and the warmed body, when if fire goes away a warmth remains which is distinct from the warmth in the fire and is an affection of the warmed body. In the same way the shape which Nature gives to the formed body must be considered as another form, distinct from Nature itself.