The strongest plea for the inceptive axis is the fact that it interlocks surface enrichment with the structure, insuring a degree of unity that might otherwise be unattainable.
The carved enrichment of [Figure 223] fully illustrates this point. The analytical study of [Figure 224] shows the diagonal used as an inceptive axis, with the leading lines grouped about it at the corner point of concentration.
Free Enrichment
Rule 8a. Free ornament for partly or fully enriched surfaces should be based and centered upon an inceptive axis of the structure.
Rule 8b. Free ornament should be related and subordinated to the structural surfaces.
Rule 8c. Points of concentration in free enrichment of vertically placed masses are usually located in and around the inceptive axis and above or below the geometric center of the design.
Center Zone Enrichment
This method of surface enrichment is used to relieve the design of heavy members in the structure or to distribute ornament over the surface of lighter parts in a piece of furniture. An example is noted in [Figure 246], [Page 128], where the upper portion of the legs has center enrichment. As can be readily seen, the enrichment is generally free in character with little or no indication of enclosure. [Figure 225] shows the application of free enrichment to a paneled screen or hinged door. The P.C. is in the upper portion of the door and is re-echoed in the door frames, while the ornament itself is strongly dynamic in movement with a decided upward tendency in sympathy with the proportions of the door. This motive might be developed by inlay, carving, or paint.
Examples of Free Enrichment
[Figure 226] is a carved Gothic leaf, appropriately used as enrichment of heavy furniture. The unit may be raised above the surface or, even more easily, depressed or incised into the surface. The small corner spot is added with the intention of bringing the leaf into sympathetic conformity with the contours. Note how the center line of both units in [Figures 225] and [226] coincides with the inceptive axis of the structure. Let it again be reiterated that this binding of the surface enrichment to the structure by means of the coincidence of the axes of symmetry and the inceptive axes causes the most positive kind of unity. No part of this form of enrichment should be carved sufficiently high to give it the appearance of being separated from the main surface.