In very primitive times when a utensil is produced functional ideas predominate, and there is, perhaps, so far as its artificial characters are concerned, a minimum of comeliness. But as the ages pass by essential features are refined and elements of beauty are added and emphasized. In riper culture the growing pressure of esthetic desire leads to the addition of many superficial modifications whose chief office is to please the fancy. In periods of deadened sensibility or even through the incompetence of individual artists in any period, such features may be ill chosen and erroneously applied, interfering with construction and use, and thus violating well founded and generally accepted canons of taste. In respect to primitive works we may distinguish four steps in the acquisition of esthetic features of form, three of which are normal, the fourth abnormal: First, we have that in which functional characters alone are considered, any element of beauty, whether due to the artist's hand or to the accidents of material, construction, or model, being purely adventitious; second, that in which the necessary features of the utensil appear to have experienced the supervision of taste, edges being rounded, curves refined, and symmetry perfected; third, that in which the functionally perfect object, just described, undergoes further variations of contour, adding to variety, unity, &c., thus enhancing beauty without interfering with serviceability; and, fourth, that in which, under abnormal influences, beauty is sought at the sacrifice of functional and constructive perfection. [Illustration: FIG. 286. Mat or tray exhibiting a minimum of esthetic attributes of form. Moki work--1/8.] The exact relations of the various classes of forces and phenomena pertaining to this theme may be more fully elucidated by the aid of illustrations. Woven mats, in early use by many tribes of men and originating in the attempt to combine leaves, vines, and branches for purposes of comfort, are flat because of function, the degree of flatness depending upon the size of filaments and mode of combination; and in outline they are irregular, square, round, or oval, as a result of many causes and influences, embracing use, construction, material, models, &c. A close approach to symmetry, where not imposed by some of the above mentioned agencies, is probably due to esthetic tendencies on the part of the artist. The esthetic interest attaching to such a shape cannot be great, unless perhaps it be regarded, as all individuals and classes may be regarded, in its possible relations to preceding, associated, and succeeding forms of art. The varied features observed upon the surface, the colors and patterns (Fig. 286), pertain to design rather than to form and will receive attention in the proper place. [Illustration: FIG. 287. Tray having decided esthetic attributes of form. Obtained from the Apache--1/2.]