Previous to the successful experiments of this gentleman, Leibnitz and Boerhaave, as well as some of the ancient philosophers, reflecting on the various gradations in the scale of animated nature, had endeavoured to prove that there might be degrees of life between the animal and the plant, and that animals might be found which would propagate by slips, like plants. These conjectures were verified by Trembley, but not in consequence of any pre-conceived ideas in favour of such a supposition; on the contrary, it was only by repeated observations that he could destroy his own prejudices, and join these wonderful beings to the animal kingdom.[106] [106] A great part of the knowledge of the ancients consisted in an extensive variety of ingenious hypotheses, the result of intense study and application; and it need not excite surprize, if, amongst a number of suppositions, some of them have since been found conformable to truth. The moderns, animated by the example of the great Bacon, by an abundance of experiments frequently repeated, and the assistance of good instruments, have introduced unquestionable demonstration in the place of speculation; this renders the present philosophy very far superior to that of the ancients. Thus it is with respect to the subject now under consideration; many of the ancients conjectured that animated beings might exist possessed of the wonderful properties of the hydra; that some of them, however, were even witnesses of the fact, cannot well be disputed; though it may be fairly presumed, that their knowledge of this animal, comparatively with that we are now in possession of, was very circumscribed and imperfect. St. Augustine relates that one of his friends performed the experiment before him, of cutting a polype in two, and that immediately the two parts thus separated betook themselves to flight, moving with precipitation different ways. The original passage is too long to be here inserted, but may be found in his work “De Quantitate Animæ,” c. 62, p. 431, col. 1.