When we come to Hume, the case is considerably altered. He opens the question after his own manner by asking _how_ the fact commonly stated can be; and using the difficulty of explaining this "how" as a sufficient objection against the fact asserted. "There are some philosophers," he writes (_Treatise_, B. I., Part iv., Sect. 6), "who imagine we are every moment intimately conscious of what we call our _self_; that we feel its existence and its continuance in existence; and are certain, beyond the evidence of a demonstration, both of its perfect identity and simplicity.... "Unluckily all these positive assertions are contrary to that very experience, which is pleaded for them, nor have we any idea of _self_, after the manner it is here explained. For from what impression could this idea he derived?... If any impression gives rise to the idea of self, that impression must continue invariably the same, through the whole course of our lives; since self is supposed to exist after that manner. But there is no impression constant and invariable. Pain and pleasure, grief and joy, passions and sensations succeed each other, and never all exist at the same time. It cannot therefore be from any of these impressions, or from any other, that the idea of self is derived; and consequently there is no such idea.... For my part, when I enter most intimately into what I call _myself_, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch _myself_ at any time without a perception, and never can observe anything but the perception.... The mind is a kind of theatre, where several perceptions successively make their appearance; pass, re-pass, glide away, and mingle in an infinite variety of postures and situations. There is properly no _simplicity_ in it at one time, nor _identity_ in different; whatever natural propension we may have to imagine that simplicity and identity. The comparison of the theatre must not mislead us. They are the successive perceptions only, that constitute the mind; nor have we the most distant notion of the place, where these scenes are represented, or of the materials, of which it is composed." It is curious that Hume wishing to represent Mind as a melting mist of successive perceptions, should be driven into the use of a word which implied a something continuing and permanent as affording the _stage_ on which all passing scenes called "impressions" are enacted.