75 
(which investigation I shall not, however, be able to follow out) 
the philosophical classification of art, this brings out more clearly 
its theoretic principles; for each form of art is grounded on a rea- 
son in the mental constitution, and depends primarily on the nature 
of the idea which strives for representation, so that every art has 
a body, as it were, in which its life freely develops itself, and in no 
other. The arts of expression by language differ from the arts of 
expression by form and color, and cannot be combined on the 
same lines of representation. Sculpture cannot perfect itself in the 
principles that apply to painting ; and a familiar example of this is 
the beautiful gate of the Baptistry of San Giovanni, in which the 
sculptor, by trying to unite the plastic and the graphic elements, or 
not keeping them distinct, fails of the highest effect. Yet the prin- 
ciples of all the arts are, in a measure, interchangeable, just as the 
laws of construction in architecture, bringing into play such ana- 
lytic qualities as order, mass and combination, may enter with 
effect into the composition of a picture and lend it unity of design 
and firmer tone. 
One German writer classifies artistic forms into two—the mathe- 
matic and the organic; in this way art appears, as it were, a second 
nature, which represents and reviews her processes. Mr. Hay, in 
his Science of Proportion in Greek Art, goes so far as to say that 
“¢all fundamental beauty of form is derived from the vibrations of 
the musical chord, and is geometric or harmonic in its development, 
and cannot fail to be reducible to mathematical law.’’ Rhythmic 
arts, at least, are governed by mathematical laws like architecture 
in its form in space, and music in its movement in time ; poetry 
also partakes of this regulated character. On the other hand, the 
arts which represent life, free life, such as landscape, animal exist- 
ence, and, above all, forms of human life in historic, gezre, and 
portrait painting, and especially in sculpture, come under the class 
of organic art, which arts are essentially imitative, but at the same 
time they stand in connection with higher ideas. Yet here, too, it 
is difficult to draw distinctions. Painting expresses, above all, qual- 
ity and character; and yet in music there is as truly quality as 
quantity of sound, character as well as harmony. Colors have a 
genuine resemblance to tone, and colors form an octave which pro- 
duces concord or discord, and gives rise to as various sensations. 
Architecture, which is abstractly geometrical, becomes also highly 
