it is potentially a universal quality in a painting. Lines may be unified according to the three modes of harmony, balance, and evolution. The repetition of the same kind of line confers a harmonious unification upon a drawing, as in Tintoretto's "Bacchus and Ariadne," where the circle is to be found repeated in the crown and ring, in the heads of the three figures, in the breasts of Ariadne. Similar to this sameness of form is sameness of direction or parallelism of lines. Another kind of harmonious unification of lines is continuity, where out of different lines or shapes a single line is made. The classical geometrical forms of composition, as the circular or pyramidal, are good examples of this. The "Odalisque" of Ingres, where all the lines of the body constitute a single line, is a notable case. What Ruskin has called "the approach, intersection, interweaving of lines, like the sea waves on the shore,"--the conspiracy of all the lines in a drawing to form one single network, of which illustrations could be found in the work of every draftsman, is a kind of harmony of line. Symmetrically disposed shapes, and lines whose directions are opposed, have the balanced form of unity. Here, from a given point as center, the attention is drawn in contrary yet equal ways. Examples of this type of composition are abundant among the Old Masters; as a rigid form it is, however, disappearing. That the dramatic type of unity is to be found in lines will be confirmed by every one who has observed the movement, the career of lines. Whenever shapes are so disposed that they form a line leading up to a given shape, wherever, again, lines converge to a single point, there is a clear case of evolution; we begin by attending to the line at a certain point, proceed in a certain direction, then reach a terminal point, the goal of the process. In Leonardo's "Last Supper," the convergence of the perspective lines and the lines formed by the groups of Apostles is a case of evolution. The different types of unification are, of course, not exclusive. In the painting just referred to, all three are present: Christ and the Apostles are arranged along a single line, the two ends of which, despite their symmetrical and balanced disposition, converge to one central point, the Christ. Every pyramidal form of composition is a combination of balance between the elements at the bases of the triangle, convergence towards the apex, and harmony through the participation of the three elements in a single form. One of the most interesting and complex types of organization of lines is rhythm--the balanced, harmonious movement of lines. A line is rhythmical when there is a balanced alternation of direction in its movement, a turning now to the right and now to the left, or vice versa; proportion in the length of the segments made by the turns; and general direction--a tending somewhere.