Although Intercolumniation consists only in regulating and determining the spaces between the columns, and consequently does not affect the nature of the composition,—for a tetrastyle, hexastyle, &c., would still be such, no matter how narrow or wide the _intercolumns_ or intervals between the columns may be,—very much depends upon it, with regard to expression and effect. How intercolumniation is regulated in the Doric Order has been already explained at page 20: in that, the distances between the columns is governed entirely by the triglyphs of the frieze, so that there can be no medium between _monotriglyphic and ditriglyphic_ intercolumniation, accordingly as there is either one or two triglyphs over each intercolumn. But in the other Orders there is no such restriction; in them the intercolumns may be made wider or narrower, as circumstances require, but of course under the guidance of judgment and good taste; for what is left _à discrétion_ is not always very discreetly used. Vitruvius and his followers, however, have not cared to trust to individual discretion or indiscretion, but have fixed certain positive and distinct modes of intercolumniation, viz. five,—perhaps out of compliment to the _five_ Orders, to wit: Pycnostyle, or _closely set_, in which the intercolumns are one diameter and a quarter, or a half, in width. Systyle, in which they are two diameters wide. Eustyle, or _well spaced_, in which they are two diameters and a half. Diastyle, in which they are three diameters. Aræostyle, or _thinly set_, in which they are four diameters. Let us repudiate for Architecture all such formal act-of-parliament legislation, and take pycnostyle and aræostyle as the greatest allowable degree of closeness or of distance at which the columns can be placed; and it follows that between such maximum and minimum any intermediate measure is admissible, and that there is no occasion to fix it positively and arithmetically, and make distinctions which are, after all, only arbitrary. There are a great many matters in design which must be left to the Architect, and intercolumniation is one of them. It is not possible to have precise rules for every thing, neither is it desirable; for if every thing in it could be done by rule, Architecture would forfeit its nature as one of the Fine Arts, and be reduced to a merely mechanical one. What is done by rule can be done by one man just as well as by another.