Glass-making. À la recherche de l’explorateur John Franklin

"O Carlyle!" exclaimed Emerson, in his diary, at the time 'Sartor Resartus' was being republished in America, 'the merit of glass is not to be seen, but to be seen through; but every crystal and lamina of the Carlyle glass shows.' With admirable precision this defines the proper function of a pane of glass. Decorative art, in casting about for new fields of conquest, has too frequently induced a contrary feeling; but, after all, a window-pane at its best is something to be seen through and not to be seen.
It is our means of looking out upon the world and letting the sun look in upon us. The more perfectly, then, it fulfills its function, the less evidence will it bear of its evolution from such dull things as sand and lime and soda-cake. Our window-pane is transparent in all things save its own history.