The source, from which is derived the pleasure of novelty, is a metaphysical inquiry of great curiosity, and will on that account excuse my here introducing it. In our waking hours whenever an idea occurs, which is incongruous to our former experience, we instantly dissever the train of imagination by the power of volition; and compare the incongruous idea with our previous knowledge of nature, and reject it. This operation of the mind has not yet acquired a specific name, though it is exerted every minute of our waking hours, unless it may be termed INTUITIVE ANALOGY. It is an act of reasoning of which we are unconscious except by its effects in preserving the congruity of our ideas; Zoonomia, Vol. I. Sect. XVII. 5. 7. In our sleep as the power of volition is suspended, and consequently that of reason, when any incongruous ideas occur in the trains of imagination, which compose our dreams; we cannot compare them with our previous knowledge of nature and reject them; whence arises the perpetual inconsistency of our sleeping trains of ideas; and whence in our dreams we never feel the sentiment of novelty; however different the ideas, which present themselves, may be from the usual course of nature. But in our waking hours, whenever any object occurs which does not accord with the usual course of nature, we immediately and unconsciously exert our voluntary power, and examine it by intuitive analogy, comparing it with our previous knowledge of nature. This exertion of our volition excites many other ideas, and is attended with pleasurable sensation; which constitutes the sentiment of novelty. But when the object of novelty stimulates us so forcibly as suddenly to disunite our passing trains of ideas, as if a pistol be unexpectedly discharged, the emotion of surprise is experienced; which by exciting violent irritation and violent sensation, employs for a time the whole sensorial energy, and thus dissevers the passing trains of ideas; before the power of volition has time to compare them with the usual phenomena of nature; but as the painful emotion of fear is then generally added to that of surprise, as every one experiences, who hears a noise in the dark, which he cannot immediately account for; this great degree of novelty, when it produces much surprise, generally ceases to be pleasurable, and does not then belong to objects of taste. In its less degree surprise is generally agreeable, as it simply expresses the sentiment occasioned by the novelty of our ideas; as in common language we say, we are agreeably surprised at the unexpected meeting with a friend, which not only expresses the sentiment of novelty, but also the pleasure from other agreeable ideas associated with the object of it.