XXII. Now, it will be noticed that, during the whole of this process, the attention is kept fixed on the forms of the penetrations, that is to say, of the lights as seen from the interior, not of the intermediate stone. All the grace of the window is in the outline of its light; and I have drawn all these traceries as seen from within, in order to show the effect of the light thus treated, at first in far off and separate stars, and then gradually enlarging, approaching, until they come and stand over us, as it were, filling the whole space with their effulgence. And it is in this pause of the star, that we have the great, pure, and perfect form of French Gothic; it was at the instant when the rudeness of the intermediate space had been finally conquered, when the light had expanded to its fullest, and yet had not lost its radiant unity, principality, and visible first causing of the whole, that we have the most exquisite feeling and most faultless judgments in the management alike of the tracery and decorations. I have given, in Plate X., an exquisite example of it, from a panel decoration of the buttresses of the north door of Rouen; and in order that the reader may understand what truly fine Gothic work is, and how nobly it unites fantasy and law, as well as for our immediate purpose, it will be well that he should examine its sections and mouldings in detail (they are described in the fourth Chapter, § xxvii.), and that the more carefully, because this design belongs to a period in which the most important change took place in the spirit of Gothic architecture, which, perhaps, ever resulted from the natural progress of any art. That tracery marks a pause between the laying aside of one great ruling principle, and the taking up of another; a pause as marked, as clear, as conspicuous to the distant view of after times, as to the distant glance of the traveller is the culminating ridge of the mountain chain over which he has passed. It was the great watershed of Gothic art. Before it, all had been ascent; after it, all was decline; both, indeed, by winding paths and varied slopes; both interrupted, like the gradual rise and fall of the passes of the Alps, by great mountain outliers, isolated or branching from the central chain, and by retrograde or parallel directions of the valleys of access. But the track of the human mind is traceable up to that glorious ridge, in a continuous line, and thence downwards. Like a silver zone-- "Flung about carelessly, it shines afar, Catching the eye in many a broken link, In many a turn and traverse, as it glides. And oft above, and oft below, appears-- * * * * to him who journeys up As though it were another."