"..can you [contemporary painters] ever get close, even vaguely, to the solidity, the transparency, the lyric strength of colour, to the clarity, the mystery, the emotion of any of the paintings of Fra Angelico, Piero della Francesca, Botticelli, Dürer, Holbein or of young Raphael? Friends, have you ever realized that with the oil colours used today this is absolutely impossible?. ..In the museums of Europe I have observed the work of the Flemish painters at length – those earlier, later as well as contemporary to the [brothers] Van Eycks – and I am convinced that the above mentioned brothers were not the discoverers of oil paint in its true sense, as is held today, but that what they did was introduce oil in emulsion with other substances, especially live and fossil resins, into so-called oil tempera emulsion, which was already known in the Flanders, to enable them through the use of veiling to give a greater finish, cleanliness and strength of colour to their painting. 'These oils which are their tempera' said Vasari, speaking of the Flemish [painters] in his Life of Antonello; and without doubt he was alluding to Flemish oil tempera emulsion, but it is sure, absolutely sure, that.. ..we are dealing with.. ..a tempera based mixture (egg, glue, resin, tempera etc) in which oil was only used as a means of unity and for the finish of the painting."