The extreme difference observable between the apparent properties of animal and inanimate matter, easily led to the opinion of something more as necessary to thought, and the phenomena of mind, than mere juxta position of the elements, whereof our bodies are composed. The very antient opinion also of a state of existence after death, prevalent in the most uncivilized as well as enlightened states of society, confirmed this opinion of a separate and immortal part of the human system: for it was sufficiently evident, that no satisfactory hopes of a futurity after death, could be founded on the perishable basis of the human body. It is only of late days, and from the extension of anatomical and physiological knowledge, that the theory, and the facts of animal organization have been at all understood; and without the conjunction of physiology with metaphysics, the latter would have remained to eternity, as it has continued for ages, a mere collection of sophisms, and a science of grammatical quibbling. The doctrine of a future state, and that of an immaterial and immortal soul, became therefore mutual supports to each other; and herein the civil power willingly joined in aid of the dogmas of metaphysical theology, from observing the convenience that might arise in the government of civil societies, from inculcating a more complete sanction of rewards and punishments for actions in this life, by means of the dispensations in a life to come. Other causes also gave an universal preponderance to the theory of the human soul. It became, for the reasons above mentioned, not only a favourite doctrine with churchmen and statesmen, but the self delusions among the vulgar, respecting supposed appearances after death, rendered it also a _popular_ doctrine. Indeed, in every age, and in every country, the priesthood have found it so powerful an engine of influence over the minds of the people, and in too many cases, so, fruitful a source of lucrative imposture, that its prevalence is not to be wondered at, wherever artificial theology has been engrafted on the simplicity of true religion, and supported by an established clergy. Of Popery, which yet remains the prevailing system of the christian world, it is doubtless the corner stone; and even under every form of ignorant and idolatrous worship throughout the globe, it is the main source of power and profit to that class of society, which regulates the religious opinions, rites and ceremonies of the country. Not that I would insinuate, that the belief of a separate soul, like some other opinions that might be mentioned, has been generally taught by professors who disbelieve it; for plausible arguments are not wanting, to give it that currency which it has so long received among the wisest and the best of men: nor that an established priesthood of any age or country, or of any religion, is a mere compound of fraud and imposture, for I well know that the wise and the good are abundant in this class