Clavis Sigillorum and Index of Manuscripts.—The author's intention to publish his MSS. (1).—The preparation of the MSS. for publication (2).—Admonition to readers (3).—The disorder in the MSS. (4).—Suggestions for the arrangement of MSS. treating of particular subjects (5—8).—General introductions to the book on painting (9—13).—The plan of the book on painting (14—17).—The use of the book on painting (18).—Necessity of theoretical knowledge (19, 20).—The function of the eye (21—23).—Variability of the eye (24).—Focus of sight (25).—Differences of perception by one eye and by both eyes (26—29).—The comparative size of the image depends on the amount of light (30—39).
II.
LINEAR PERSPECTIVE
General remarks on perspective (40—41).—The elements of perspective:—of the point (42—46).—Of the line (47—48).—The nature of the outline (49).—Definition of perspective (50).—The perception of the object depends on the direction of the eye (51).—Experimental proof of the existence of the pyramid of sight (52—55).—The