beyond himself, and by which he is plainly discover'd to have relation to some other Being or Nature besides his own; then will this Animal undoubtedly be esteem'd a Part of some other System. For instance, if an Animal has the Proportions of a Male, it shews he has relation to a Female. And the respective Proportions both of the Male and Female will be allow'd, doubtless, to have a joint-relation to another Existence and Order of things beyond themselves. So that the Creatures are both of 'em to be consider'd as Parts of another System: which is that of a particular Race or Species of living Creatures, who have some one common Nature, or are provided for, by some one Order or Constitution of things subsisting together, and co-operating towards their Conservation and Support.
In the same manner, if a whole Species of Animals contribute to the Existence or Well-being of some other; then is that whole Species in general, a Part only of some other System.
For instance; To the Existence of the Spider, that of the Fly is absolutely necessary. The heedless Flight, weak Frame, and tender Body of this latter Insect, fits and determines him as much a Prey, as the rough Make, Watchful-ness,
