[Note] that things that are nourished by nature and increase because of this have a limit of [their] increase, and their increase toward the [proper] measure is limited; but neither the nourishment nor the increase of fire is limited. Therefore fire is not nourished and increased in a similar manner to things endowed with life. But if [fire] is not [nourished and increased] similarly, then it would not be a cause of nourishment and increase for the things endowed with life, either. But such a movement of fire would be generation rather than increase or nourishment. This alone of the elements was thought to be nourished and to increase, because in the other [elements] the excess is clearly an addition. For when water is added to water, and earth to earth, thus an excess arises. But fire is in excess not when fire is added, but when heterogeneous matter [has been added], such as timbers or things of that sort; and when these things are changed by the force of fire into the same substance, thus the excess of fire arises.