e painter uses pigment, as oil-color or
water-color or tempera, laid upon a surface, as canvas, wood, paper,
plaster; this material pigment is his vehicle. The etcher employs
inked scratches upon his plate of zinc or copper, bitten by acid or
scratched directly by the needle; these marks of ink are the vehicle
of etching. To the way in which the artist uses his medium for
practical expression and to his methods in the actual handling of his
vehicle is applied the term technique. The general conception of his
picture, its total design, the choice of motive, the selection of details,
the main scheme of composition,--these belong to the great strategy
of his art. The application of these principles in practice and their
material working out upon his canvas are an affair of tactics and fall
within the province of technique.

The ultimate significance of a work of art is its content of emotion,
the essential controlling idea, which inspires the work and gives it
concrete form. In its actual embodiment, the expressive power of the
work resides in the medium. The medium of any art, then, as color
and mass in painting, line in drawing and etching, form in sculpture,
sound in music, is its means of expression and constitutes its
language. Now the signification of language derives from
convention. Line, for example, which may be so sensitive and so
expressive, is only an abstraction and does not exist in nature. What
the draughtsman renders as line is objectively in fact the boundary
of forms. A head, with all its subtleties of color and light and shade,
may be represented by a pencil or charcoal drawing, black upon a
white surface. It is not the head which is black and white, but
the drawing. Our acceptance of the drawing as an adequate
representation of the head rests upon convention. Writing is an
elementary kind of drawing; the letters of the alphabet were
originally pictures or symbols. So to-day written or printed letters
are arbitrary symbols of sounds, and grouped together in arbitrary
combinations they form words, which are symbols of ideas. The
word _sum_ stood to the old Romans for the idea "I am;" to
English-speaking people the word signifies a "total" and also a problem in
arithmetic. A painting of a landscape does not attempt to imitate the
scene; it uses colors and forms as symbols which serve for
expression. The meaning attaching to these symbols derives from
common acceptance and usage, Japanese painting, render