All this has been shewn with great force of argument and ingenuity by Dr. Priestley in these disquisitions, to which it may safely be affirmed nothing like a satisfactory answer has yet been given, or is ever likely to be given. True metaphysics, like every other branch of philosophy can only be founded on an accurate observation of facts, and as these become gradually substituted for mere names, our real knowledge will improve. It is to physiology perhaps that the question of the materiality of the human soul, and even that of liberty and necessity will owe the compleatest elucidation. Until medical writers brought into view the _facts_ relating to animal life, the metaphysical disquisitions on these subjects were involved in an endless confusion of words without precise meaning, and almost always including in their definition a _petitio principii_. Indeed we are not yet fully apprized either in Law, Physic or Divinity any more than in Metaphysics, that the _species intelligibiles_ of the old schoolmen, and the whole class of abstract ideas of the new schoolmen with Locke at their head, are not things, but names. They are not even either sensations or ideas; they are words, convenient indeed for classification, and used artificially like the signs of Algebra, but they have no archetype. This is a subject which will probably be better understood ere long by the labours of Mr. Horne Tooke. Dr. Priestley therefore considered the question of a future state, as now rested on the basis which to a christian is or ought to be perfectly satisfactory; on the promises and declarations of our Saviour, exemplified by his own resurrection from the dead. Indeed the circumstances of the whole question of futurity depending on the truth of the christian scriptures and on them alone, is calculated to give them a peculiar and inestimable value in the eyes of those who look forward with anxious hope[69] to a continued and more perfect state of existence after death. Nor is it of any consequence to the christian, that the manner how this will be effected is not plainly revealed; for it is sufficient that the Being who first gave animation to the human frame, will at his own time and in his own manner for the wisest and best of purposes, again exert the same act of almighty power in favour of the human race, and in fulfillment of his promise through Jesus Christ. Such at least was the view of the subject habitually entertained by our author. [69] There are some persons who do not seem to entertain this anxious hope. Mr. Gray the poet seems an instance, from the following passage in his ode Barbaras Ædes aditure mecum (Letters V. 2 p. 44) though I do not recollect that the sentiment has been noticed before.