The most original features of Egyptian sculpture and its arrested development must, then, be referred, on the one hand to the nature of the materials employed, and, on the other, to the habits contracted during many centuries of ideographic writing.[306] It has long been the fashion to attribute capital importance to what is called a canon, in describing the origin of the Egyptian style. The ideas which have been published on this question seem to us manifestly exaggerated; we must examine them a little closely. [306] M. CH. BLANC had a glimmering of the great influence exercised over the plastic style of Egypt by the hieroglyphs; see his _Voyage dans la Haute-Égypte_, p. 354. The word _canon_ comes from the Greek κάνων, a _rule_. As applied to the arts it has been defined as "a system of measurements by the use of which it should be possible to tell the size of any part by that of the whole, or the size of the whole by that of any one of its parts."[307] The idea of proportion, upon which every canon must rest, is a creation of the brain. A canon, therefore, is the result of those searching and comprehensive generalizations of which only races with great intellectual gifts are capable. Each of the arts may have its canon, or rule of proportion, establishing a proper relation between all the elements of its creations and easily expressible in figures. [307] _Dictionnaire de l'Académie des Beaux-Arts_, under the word _Canon_. The finest examples of a canon as applied to architecture are furnished by the Greek orders. Given the smallest member of an Ionic or Doric order, the dimensions of all the other members of the column and its entablature may be calculated with almost complete accuracy. There is nothing of the kind in Egyptian architecture. There is no constant proportion between the heights and thicknesses of the shaft, the capital, and the entablature; there is no constant relation between their shapes. In a single building, and in a single order, we find proportions varying between one hall or court and another. The word _canon_ has an analogous sense when applied to sculpture. We establish a canon when we say that a figure should be so many heads high, and that its limbs should bear a certain proportion to the same unit. It would be the same if, as has often been proposed, the medius of the hand were erected into the unit of measurement, except that the figure would then be divided into a larger number of parts. Both ancients and moderns have investigated this question, but we need not dwell upon the results of their inquiries. The Greeks had the canon of Polycletus; the Romans that of Vitruvius, while Leonardo da Vinci set an example to the numerous artists who have investigated the question since his time.[308] [308] These researches are described in the chapter entitled _Des Proportions du Corps Humain_ of M. CH. BLANC'S _Grammaire des Arts du Dessin_, p. 38.