I began to engrave the Mona Lisa in 1829 at Loro in the Marche, where I had to go for a change of air. Subsequently for a long period of years I could work on it only during the night, as I had to give my attention to the works that were commissioned from me. I experienced a great difficulty in engraving it, in view of the largeness and the forcefulness of the coloring. This can be obtained easily through broad and heavy cuts [but] in the Mona Lisa there are many details and finesses in the background, very many more in the folds of the veil that covers her and quite a few in the hair that I had to treat all in fine and strict work, and so the difficulty became greater. I know of no object more difficult to be followed in engraving…. The difficulty of the engraving is to be able to obtain, on the basis of an object, that it should be of the same material, of the same stuff and substance, alike in the clear, in the middle tints, and in the dark ones, and this is what I have sought with much effort through the combination of cuts and points. This is the thankless métier of the engraver, which is not appreciated and not even observed by almost anybody: to make it really felt through this work alone that this cloth is of silk, of veil, or of velvet, in all the movements made by the folds, is not an easy thing, any more than all the infinite varieties that a good engraver must express through the burin, to the end that everything can say—I am marble, wool, water, skin, etc.