Considering the length of his career, he produced surprisingly little work; important prints by him are now rarer than those of any other artist of this period. His pillar-prints, which are particularly fine, have been for many years proverbially few. As a rule only his earlier prints are signed. His surimono are, however, generally signed with the brush-name Kosuisai. Sheets from his numerous books are often mounted as separate prints. Collectors differ in their opinions as to whether it is advisable thus to take to pieces the sheets of a bound volume, such as the "Green Houses." Any such act, in dealing with art treasures, should be approached only after careful consideration; but it seems in this case a desirable method of preserving and exhibiting what are, after all, wholly separate pictures. V THE THIRD PERIOD: KIYONAGA AND HIS FOLLOWERS FROM THE MATURITY OF KIYONAGA TO HIS RETIREMENT (1780-1790) CHAPTER V THE THIRD PERIOD: KIYONAGA AND HIS FOLLOWERS FROM THE MATURITY OF KIYONAGA TO HIS RETIREMENT (1780-1790). With the fully developed and complex technique which had been brought to perfection by the time of Harunobu's death, the colour-print took on a new richness of expression and reached its culmination in the Third Period. Generalizations attempting to define the difference between the work of this and the preceding periods are perilous; but we shall perhaps not be venturing too dangerously if we summarize the change of attitude as a step toward naturalism combined with a deepening of ideal significance. In the period of the Primitives the artistic impulse was almost wholly one of decoration--an attempt to express in line and colour the great themes of design that stirred within the brain of the artist. The Primitives were inspired by what Von Seidlitz calls the desire of "presenting single characteristic motives of movement." Their creations had no relation to observed fact or to an exact rendering of Nature; they were the shadows of lofty dreams of form projected by the luminous spirit of the artist against the wall of space.