I have been led into these observations, on the various parts of the corporeal process which precedes sensation, by the desire of removing, as much as possible, any obscurity in which your notions on the subject might be involved,--as I know well the influence which even a slight confusion in our notion of any _part_ of a complicated process has, in spreading, as it were, its own darkness and perplexity over parts of the process, which otherwise we should have found no difficulty in comprehending. You might think, that you knew less distinctly the mental sensation itself, because you knew only obscurely the series of bodily changes that precede sensation; but still it must be remembered, that it is only the _last_ link of the corporeal chain,--the ultimate affection of the sensorial organ, in whatever manner and to whatever extent it may be affected,--immediately antecedent to the affection of the mind, which is to be considered as that with which nature has united the corresponding change in our mental frame. This mysterious influence of our _bodily_ on our _mental_ part has been poetically compared to that which the sun was supposed to exercise on a lyre, that formed part of a celebrated Egyptian statue of Memnon, which was said to become musical when struck with its beams; and though the poet has extended the similitude, beyond our mere elementary sensations, to the complex perception of beauty, it is still a very happy illustration--as far as a mere poetic image can be an illustration--of the power which matter exercises over the harmonies of mind:-- “For as old Memnon's image, long renown By fabling Nilus, to the quivering touch Of Titan's ray with each repulsive string Consenting, sounded through the warbling air Unbidden strains,--even so did Nature's hand, To certain species of external things Attune the finer organs of the mind. So the glad impulse of congenial powers, Or of sweet sound, or fair proportion'd form, The grace of motion, or the bloom of light, Thrills through Imagination's tender frame, From nerve to nerve. All naked and alive, They catch the spreading rays; till now the soul At length discloses every tuneful spring, To that harmonious movement from without. Responsive. Then the charm, by Fate prepar'd Diffuses its enchantment.[72] Fancy dreams Of sacred fountains, and Elysian groves, And vales of bliss! the Intellectual Power Bends from his awful throne a wondering ear, And smiles; the Passions, gently soothed away, Sink to divine repose; and Love and Joy Alone are waking.”[73]