Meditations by Marcus Aurelius Book 9 Page 9

VII. Of all unreasonable creatures, there is but one unreasonable soul; and of all that are reasonable, but one reasonable soul, divided betwixt them all.

As of all earthly things there is but one earth, and but one light that we see by; and but one air that we breathe in, as many as either breathe or see. Now whatsoever partakes of some common thing, naturally affects and inclines unto that whereof it is part, being of one kind and nature with it. Whatsoever is earthly, presseth downwards to the common earth. Whatsoever is liquid, would flow together. And whatsoever is airy, would be together likewise. So that without some obstacle, and some kind of violence, they cannot well be kept asunder. Whatsoever is fiery, doth not only by reason of the elementary fire tend upwards; but here also is so ready to join, and to burn