John Ruskin,
Ariadne Florentina: Six Lectures on Wood and Metal Engraving
“ I shall speak only of wood and metal engraving. But there is one circumstance in stone engraving which it is necessary to observe in connection with the other two branches of the art.The great difficulty for a primitive engraver is to make his scratch deep enough to be visible. Visibility is quite as essential to your fame as permanence; and if you have only your furrow to depend on, the engraved tablet, at certain times of day, will be illegible, and passed without notice. ”
