3.  The surface of animals, is also covered with other animals, which are in the same manner the basis of other animals that live upon it:  nay, we find in the most solid bodies, as in marble itself, innumerable cells and cavities, that are crowded with such imperceptible inhabitants, as are too little for the naked eye to discover.  On the other hand, if we look into the more bulky parts of nature, we see the seas, lakes, and rivers teeming with numberless kinds of living creatures; we find every mountain and marsh, wilderness and wood plentifully stocked with birds and beasts, and every part of matter affording proper necessaries and conveniences for the livelihood of multitudes which, inhabit it.

4.  The author of the Plurality of Worlds draws a very good argument from this consideration, for the peopling of every planet:  as indeed it seems very probable, from the analogy of reason, that if no part of matter, which we are acquainted with, lies waste and useless, those great bodies; which are at such a distance from us, should not be desert and unpeopled, but rather that they should be furnished with beings adapted to their respective situations.

5.  Existence is a blessing to those beings only which are endowed with perception, and is in a manner thrown away upon dead matter, any further than it is subservient to beings which are conscious of their existence.  Accordingly we find, from the bodies which lie under our observation, that matter is only made as the basis and support of animals, and that there is no more of the one, than what is necessary for the existence of the other.

6.  Infinite goodness is of so communicative a nature, that it seems to delight in the conferring of existence upon every degree of perceptive being.  As this is a speculation, which I have often pursued with great pleasure to myself, I shall enlarge further upon it, by considering that part of the scale of beings which comes within our knowledge.

7.  There are some living creatures which are raised but just above dead matter.  To mention only that species of shell-fish, which are formed in the fashion of a cone, that grow to the surface of several rocks and immediately die upon their being severed from the place where they grow:  there are many other creatures but one remove from these, which have no other sense besides that of feeling and taste.  Others have still an additional one of hearing; others of smell; and others of sight.

3.  It is wonderful, to observe, by what a gradual progress the world of life advances through a prodigious variety of species, before a creature is formed that is complete in all its senses:  and even among these there is such a different degree of perfection in the sense which one animal enjoys beyond what appears in another, though the sense in different animals is distinguished by the same common denomination; it seems almost of a different nature.