dangerous; and the philosophy which admits them as principles of general knowledge deserves ill to be reputed philosophy. It would have been just as useful, and much more safe, to admit into this receptacle of axioms those self-evident and necessary truths alone of which we have an immediate perception, since they are not confined to any special parts of science, but are common to several, or to all. Thus these profitable axioms, “What is, is,” “The whole is bigger than a part,” and divers others, might serve to enlarge the spring-head of a first philosophy, and be of excellent use in arguing _ex prœcognitis et prœconcessis_. If you ask me now what I understand then by a first philosophy, my answer will be such as I suppose you already prepared to receive. I understand by a first philosophy, that which deserves the first place on account of the dignity and importance of its objects, natural theology or theism, and natural religion or ethics. If we consider the order of the sciences in their rise and progress, the first place belongs to natural philosophy, the mother of them all, or the trunk, the tree of knowledge, out of which, and in proportion to which, like so many branches, they all grow. These branches spread wide, and bear even fruits of different kinds. But the sap that made them shoot, and makes them flourish, rises from the root through the trunk, and their productions are varied according to the variety of strainers through which it flows. In plain terms, I speak not here of supernatural, or revealed science; and therefore I say that all science, if it be real, must rise from below, and from our own level. It cannot descend from above, nor from superior systems of being and knowledge. Truth of existence is truth of knowledge, and therefore reason searches after them in one of these scenes, where both are to be found together, and are within our reach; whilst imagination hopes fondly to find them in another, where both of them are to be found, but surely not by us. The notices we receive from without concerning the beings that surround us, and the inward consciousness we have of our own, are the foundations, and the true criterions too, of all the knowledge we acquire of body and of mind: and body and mind are objects alike of natural philosophy. We assume commonly that they are two distinct substances. Be it so. They are still united, and blended, as it were, together, in one human nature: and all natures, united or not, fall within the province of natural philosophy. On the hypothesis indeed that body and soul are two distinct substances, one of which subsists after the dissolution of the other, certain men, who have taken the whimsical title of metaphysicians, as if they had science beyond the bounds of Nature, or of Nature discoverable by others, have taken likewise to themselves the doctrine of mind; and have left that of body, under the name of physics, to a supposed inferior order of philosophers.