after all, to lay itself down again with a very puzzled expression—­and acknowledge that of its very self, itself knows little or nothing!  ‘I am material,’ exclaims one of those whimsical beings, to whom the heaven-descended ‘Know thyself’ would seem to have been ironically addressed.  ‘No!—­immaterial,’ says another.  ’I am both material and immaterial,’ exclaims, perhaps, the very same mind at different times.  ‘Thought itself may be matter modified,’ says one.  ‘Rather,’ says another of the same perplexed species, ’matter is thought modified; for what you call matter is but a phenomenon.’  But are independent and totally distinct substances, mysteriously, inexplicably conjoined,’ says a third.  ’How they are conjoined we know no more than the dead.  Not so much, perhaps.’  ‘Do I ever cease to think,’ says the mind to itself, ‘even in sleep?  Is not my essence thought?’ ’You ought to know your own essence best,’ all creation will reply.  ’I am confident,’ says one, ’that I never do cease to think,—­not even in the soundest sleep.’  ‘You do, for a long time, every night of your life,’ exclaims another, equally confident and equally ignorant.  ’Where do I exist?’ it goes on.  ’Am I in the brain?  Am I in the whole body?  ’Am I anywhere?  Am I nowhere?’ ’I cannot have any local existence, for I know I am immaterial,’ says one.  ’I have a local existence, because I am material,’ says another.  ’I have a local existence, though I am not material,’ says a third.  ‘Are my habitual actions voluntary,’ it exclaims, ’however rapid they become; though I am unconscious of these volitions when they have attained a certain rapidity; or do I become a mere automaton as respects such actions? and therefore an automaton nine times out of ten, when I act at all?’ To this query two opposite answers are given by different minds; and by others, perhaps wiser, none at all; while, often, opposite answers are given by the same mind at different times.  In like manner has every action, every operation, every emotion of the mind been made the subject of endless doubt and disputation.  Surely if, as Soame Jenyns imagined, the infirmities of man, and even graver evils, were permitted in order to afford amusement to superior intelligences, and make the angels laugh, few things could afford them better sport than the perplexities of this child of clay engaged in the study of himself.  ‘Alas,’ exclaims at last the baffled spirit of this babe in intellect, as he surveys his shattered toys—­his broken theories of metaphysics, ’I know that I am; but what I am—­where I am—­even how I act—­not only what is my essence, but what even my mode of operation,—­of all this I know nothing; and, boast of reason as I may, all that I think on these points is matter of opinion—­or is matter of faith!’ He resembles, in fact, nothing so much as a kitten first introduced to its own image in a mirror:  she runs to the back of it, she leaps over it, she turns and twists, and jumps and frisks, in all directions, in the vain attempt to reach the fair illusion; and, at length, turns away in weariness from that incomprehensible enigma—­the image of herself.