In all appeals the decorative artist can make to the brain through the eye, he has open to him two distinct channels of communication in making out the scheme of his ornamentation,--the one by employing conventional forms,--and the other by introducing representations of natural objects. In the former he usually eschews light, shade, and accidental effects altogether; and in the latter he aims at reproducing the aspect of the object he depicts as nearly as possible as it appears to him. Both modes have found favour in the eyes of the great illuminators of old, and by the best they have been frequently and successfully blended. Under the "conventional" series maybe classed all productions dependent on either an Oriental or Hiberno-Saxon origin; among the "natural," the later, Netherlandish, Italian, and French illuminations may be generally grouped; and, in a mixed style, the majority of the book-decorations of the Mediæval period. To be enabled to recognize intuitively how to blend or contrast, to adopt or avoid, these different modes of treatment of ornament, is given to but few, and is revealed to those few only, after years of study and of practice. Rules may assist,[100] but can never suffice to communicate the power; work of the most arduous kind, and persistent observation, can alone bestow it. Still, with good models upon which to base his variations, and goodwill, the amateur may do much, and will probably best succeed by recurring incessantly to Nature, and combining direct, or nearly direct, imitation of Nature with geometrical lines and masses of colour symmetrically disposed. To aid his footsteps in this direction, I know no more convenient councillor than Mr. Llewellyn Jewitt, whose historical introduction to his brother's "Manual of Illuminated and Missal Painting" contains some just remarks upon the subject.[101]