Imagination is said to be the simple apprehension of corporeal objects when they are absent; which absence of the object it contemplates, distinguishes this faculty from _sensation_, and has occasioned some metaphysicians to call it _recorded sensation_. Upon the due regulation, and proper management, of this great and extraordinary power of the mind, depends, in a great measure, the happiness or misery of life. It ought to consist of a happy combination of those ideas we receive through the organs of bodily sense, and those which we derive from the faculties of moral perception; but it too frequently consists of a capricious and ill-formed mixture of heterogeneous images, which though true in themselves, are false in the way they are applied. Thus a person, the circulation of whose blood in any particular member is suddenly stopped, _imagines_ that needles are pricking the disordered part. The sensation in this case is real, but the conclusion from it is fallacious. So in every mental illusion, imagination, when she first begins to exercise her powers, seizes on some fact, of the real nature of which the mind has but an obscure idea, and, for want of tracing it through all its connexions and dependences, misleads reason into the darkest paths of error. The wild conjectures, and extravagant opinions which have issued from this source are innumerable. The imagination receives every impulse with eagerness, while the passions crowd around her splendid throne, obedient to her dictates. They act, indeed, reciprocally on each other. The imagination pours a concourse of contrary ideas into the mind, and easily disregards, or reconciles their incongruities. The voice of the calm inquirer, reason, is incapable of being heard amidst the tumult; and the favorite image is animated and enlarged by the glowing fire of the passions. No power remains to control or regulate, much less to subdue, this mental ray, which inflames the whole soul, and exalts it into the fervor of enthusiasm, hurries it into the extravagance of superstition: or precipitates it into the furious frenzies of fanaticism. The powerful tumult reigns in every part, Pants in the breast, and swells the rising heart.