“Too frequently in conversational language and even in the writings of grave authors,” says M. Ernest Breton, “the word _fresco_ is made synonymous with mural painting in general. This confusion of terms has sometimes caused the most fatal errors. The etymology of the word is the best definition of the subject. The Italians give the name of paintings _in fresco_ or _a fresco_, that is to say, _à frais_, or _sur le frais_, to those works executed upon damp stucco into which the colour penetrates to a certain depth. The ancient French authors, preserving the difference existing between the Italian _fresco_ and the French _frais_, wrote the word _fraisque_. At the present day Italian orthography has prevailed, and with us this word has now more relation to its etymology than its real signification.” Whatever may be the common acceptation of the word, we must, in order to keep within the limits of our subject, here only take into consideration real frescoes, or in other words, works of art executed upon a bare wall, properly prepared for the purpose, with which they are as it were incorporated; for in the roll of art all are excluded from the catalogue of mural paintings, rightly so called, which, although applied to walls either directly or by the aid of panels or fixed canvas, are produced otherwise than with water-colours, and used in such a manner as to penetrate the special kind of plaster with which the wall had been previously covered. We will mention as a striking example of this the famous “Lord’s Supper” of Leonardo da Vinci, which has many times been called a fresco (it is well known to have been painted upon the wall of the refectory of Santa Maria della Gratia, at Milan), but is nothing but a painting in distemper[32] on a dry partition--a circumstance, by-the-bye, which has not a little contributed to the deterioration of this magnificent work. Fresco has long been considered the most ancient style of painting. Vasari, who wrote in the middle of the sixteenth century, says in apt terms that “the ancients generally practised painting _in fresco_, and the first painters of the modern schools have only followed the antique methods;” and, in our own day, Millin, in his “Dictionnaire des Beaux-Arts,” asserts that the great paintings in the “Pœcile” of Athens and the “Lesche” of Delphi, by Panænus and Polygnotus, spoken of by Pausanias, were executed by this process; the same author also ranks among frescoes the numerous paintings left by the Egyptians in their temples and catacombs. “It was,” he remarks, “what the Romans called _in udo pariete pingere_ (to paint on a damp wall); they say _in cretula pingere_ (to paint on chalk) to designate water-colour painting on a dry ground.”