[Illustration: PLATE VIII. WHITE EAGLE. SUNG PERIOD Collection of R. Petrucci.] At that time there prevailed the analytic, painstaking, detailed and very considered drawing that is common to all periods preceding great constructive work. This technique admitted the use of two fundamental methods: one called _double contour_, the other _contour_ or _single contour_. The method of _double contour_ was applied chiefly to the drawing of plant life in landscape. It consisted in outlining leaves or branches by means of two lines of ink placed in apposition. The space thus enclosed was filled with color. Any peculiarities of formation, knots in wood and veins in leaves were added subsequently. The name of _single contour_ was applied to drawings wherein a single ink line outlined the object, the space enclosed being then filled with color. If the application of these analytic methods was sometimes carried to the extreme of delicacy it never became labored. Throughout its entire evolution the art of the T'ang period is characterized by a sense of the magnificent. Once the study of forms was exhausted, this type of work was bound to be superceded. Wu Tao-tzŭ profited by the work of his predecessors. Combining in a single stroke of the brush, vigor and an eclectic character of line, with values and fluidity of tone, he brought to a supreme unity the two great principles by which things are made manifest in all the magic of their essential structure. But it must be understood that this patient investigation of forms was not limited to preparing the way for a single master. The logical outcome was an independent movement to which the origin of modern Chinese painting can be traced. "Painting has two branches," the books say, "that of the North and that of the South; the separation occurred in the T'ang period." These terms _Northern School_ and _Southern School_ must not be taken literally. They serve merely to characterize styles which, in the eighth century, liberated themselves from methods demanding such close study and exact definition of forms. The style of the Northern School is strong, vehement and bold; the style of the Southern School is melancholy and dreamy. The ideal of Northern China, impregnated with barbarian elements, is brought into contrast with that of Southern China, heir to an already ancient civilization, and under the spell of Taoist legends and the bewildered dreams of its philosophers.[11] [11] These divisions of Northern and Southern Schools do not correspond, as might be imagined, to geographical limitations. Painters of the South worked in the style of the North and painters of the North likewise used the Southern style. Moreover the same master was able to employ one or the other according to the inspiration of the moment. These works were produced for a receptive people capable of understanding both styles.