Now, if we were never in the habit of seeing anything but real marbles, this language of theirs would soon begin to be understood; that is to say, even the least observant of us would recognize such and such stones as forming a peculiar class, and would begin to inquire where they came from, and, at last, take some feeble interest in the main question, Why they were only to be found in that or the other place, and how they came to make a part of this mountain, and not of that? And in a little while, it would not be possible to stand for a moment at a shop door, leaning against the pillars of it, without remembering or questioning of something well worth the memory or the inquiry, touching the hills of Italy, or Greece, or Africa, or Spain; and we should be led on from knowledge to knowledge, until even the unsculptured walls of our streets became to us volumes as precious as those of our libraries. § XLIII. But the moment we admit imitation of marble, this source of knowledge is destroyed. None of us can be at the pains to go through the work of verification. If we knew that every colored stone we saw was natural, certain questions, conclusions, interests, would force themselves upon us without any effort of our own; but we have none of us time to stop in the midst of our daily business, to touch and pore over, and decide with painful minuteness of investigation, whether such and such a pillar be stucco or stone. And the whole field of this knowledge, which Nature intended us to possess when we were children, is hopelessly shut out from us. Worse than shut out, for the mass of coarse imitations confuses our knowledge acquired from other sources; and our memory of the marbles we have perhaps once or twice carefully examined, is disturbed and distorted by the inaccuracy of the imitations which are brought before us continually. § XLIV. But it will be said, that it is too expensive to employ real marbles in ordinary cases. It may be so: yet not always more expensive than the fitting windows with enormous plate glass, and decorating them with elaborate stucco mouldings and other useless sources of expenditure in modern building; nay, not always in the end more expensive than the frequent repainting of the dingy pillars, which a little water dashed against them would refresh from day to day, if they were of true stone. But, granting that it be so, in that very costliness, checking their common use in certain localities, is part of the interest of marbles, considered as history. Where they are not found, Nature has supplied other materials,--clay for brick, or forest for timber,--in the working of which she intends other characters of the human mind to be developed, and by the proper use of which certain local advantages will assuredly be attained, while the delightfulness and meaning of the precious marbles will be felt more forcibly in the districts where they occur, or on the occasions when they may be procured.