the execution of it.  In this treatise the Doctor has demonstrated, that we see certain colours, not only with greater ease and distinctness, but with relief and pleasure, after having for some time contemplated other certain colours; as green after red, or red after green; orange after blue, or blue after orange; yellow after violet, or violet after yellow.  This he shews arises from the ocular spectrum of the colour last viewed coinciding with the irritation of the colour now under contemplation.  Now as the pleasure we receive from the sensation of melodious notes, independent of the previous associations of agreeable ideas with them, must arise from our hearing some proportions of sounds after others more easily, distinctly, or agreeably; and as there is a coincidence between the proportions of the primary colours, and the primary sounds, if they may be so called; he argues, that the same laws must govern the sensations of both.  In this circumstance, therefore, consists the sisterhood of Music and Painting; and hence they claim a right to borrow metaphors from each other; musicians to speak of the brilliancy of sounds, and the light and shade of a concerto; and painters of the harmony of colours, and the tone of a picture.  Thus it was not quite so absurd, as was imagined, when the blind man asked if the colour scarlet was like the sound of a trumpet.  As the coincidence or opposition of these ocular spectra, (or colours which remain in the eye after having for some time contemplated a luminous object) are more easily and more accurately ascertained, now their laws have been investigated by Dr. Darwin, than the relicts of evanescent sounds upon the ear; it is to be wished that some ingenious musician would further cultivate this curious field of science:  for if visible music can be agreeably produced, it would be more easy to add sentiment to it by the representations of groves and Cupids, and sleeping nymphs amid the changing colours, than is commonly done by the words of audible music.

B. You mentioned the greater length of the verses of Homer and Virgil.  Had not these poets great advantage in the superiority of their languages compared to our own?

P.  It is probable, that the introduction of philosophy into a country must gradually affect the language of it; as philosophy converses in more appropriated and abstracted terms; and thus by degrees eradicates the abundance of metaphor, which is used in the more early ages of society.  Otherwise, though the Greek compound words have more vowels in proportion to their consonants than the English ones, yet the modes of compounding them are less general; as may be seen by variety of instances given in the preface of the Translators, prefixed to the SYSTEM OF VEGETABLES by the Lichfield Society; which happy property of our own language rendered that translation of Linneus as expressive and as concise, perhaps more so than the original.