"Just as the twig is bent the tree's inclined."
In dealing with angular motives the same principle would be followed, but corresponding to the difference of motive. Let the form of your detail be reflected in the character of your mass.
I have spoken of the necessity in designing of seeking correspondences in form, and although, could we place every form in proper sequence and supply all the intermediary links to unite them harmoniously, forms of extreme diversity might thus be associated, given great extension of space (as in wall decoration, for instance), even then we should want these forms to correspond and recur. Yet, as a rule, having to deal in design with what are really parts rather than wholes, we can only endeavour by making the design of these parts simple and harmonious in line and form, and true to their special conditions, to render their association decoratively possible.
Certain forms seem to lend themselves to design in ornament better than others, because they give the designer certain lines and masses which can be harmoniously repeated or combined with other allied forms or lines. Design from this point of view becomes a search for analogies of form.
Analogies of Form
I mentioned certain simple geometric forms common to nature and art. Early ornament consists in the repetition of such forms. The next step was to connect them by lines: and so form and line, through endless vicissitudes and complexities, became united, to live happily in the world of decorative motive ever after. But long after the primitive unadorned geometric forms themselves have ceased to be the chief forms in ornament, their controlling influence is asserted over the boundaries of the more complicated masses introduced.