By all the Tryals yet made upon animal Substances, they are resoluble into the same Parts with Vegetables, only differently modified; that is, as we saw before, Water, Earth, Salt and Oyl, the specifick Spirit being no other than Water impregnated with the specifick and highest rectified Oyl and Salt, the Water and Earth in both are individually the same; and though there be good Reason to imagine, that there is originally but one Oyl in Nature, and that the fixt Salt of Vegetables, and the volatile Salt of Animals, may be originally the same, since transmutable into one another; yet it is necessary to examine these two Principles in animal Substances, that by comparing them with what we before discovered in Vegetables, we may have some Notion of their Differences with Regard to their Use in Diet. The great Excess of animal Heat and Motion, beyond what is necessary to Vegetables, the stronger and quicker Circulation of their Juices, necessarily require and occasion that the Oyls and Salts in animal Bodies should be differently modified from what they are in Vegetables. No Motion is performed in Animals without some Portion of Oyl, and perhaps Water too, to lubricate the Parts, and keep them supple; the Attrition would cause great Mischief, make the Motion uneasy, wear away and burn up the Parts, if they were not softned and moistned by an oily Fluid; and accordingly we find all the Muscles, Tendons, Joints and other Parts employ’d in Motion, to have Repositories of this Oyl placed about them, and that so artificially, that the Very Motion occasions the Diffusion of this Oyl upon them. There is an innate Principle of Heat or Fire, that attends the vital Powers, that may very well occasion the Change and Volatilization of Salts in animal Substances, in the same Manner as was before observed in the Putrefaction of Vegetables. Animal Oyls differ according to the Principles inherent in them, for when freed from Earth and Salts (which is very difficult by Reason of their mutual Attractions under certain Circumstances) they appear to be simple and unactive, and the same in all animal Bodies.