But this is not all, nor the best part of the work of iron. Its service in producing these beautiful stones is only rendered to rich people, who can afford to quarry and polish them. But Nature paints for all the world, poor and rich together: and while, therefore, she thus adorns the innermost rocks of her hills, to tempt your investigation, or indulge your luxury,--she paints, far more carefully, the outsides of the hills, which are for the eyes of the shepherd and the ploughman. I spoke just now of the effect in the roofs of our villages of their purple slates: but if the slates are beautiful even in their flat and formal rows on house-roofs, much more are they beautiful on the rugged crests and flanks of their native mountains. Have you ever considered, in speaking as we do so often of distant blue hills, what it is that makes them blue? To a certain extent it is distance; but distance alone will not do it. Many hills look white, however distant. That lovely dark purple colour of our Welsh and Highland hills is owing, not to their distance merely, but to their rocks. Some of their rocks are, indeed, too dark to be beautiful, being black or ashy gray; owing to imperfect and porous structure. But when you see this dark colour dashed with russet and blue, and coming out in masses among the green ferns, so purple that you can hardly tell at first whether it is rock or heather, then you must thank your old Tunbridge friend, the oxide of iron. But this is not all. It is necessary for the beauty of hill scenery that Nature should colour not only her soft rocks, but her hard ones; and she colours them with the same thing, only more beautifully. Perhaps you have wondered at my use of the word "purple," so often of stones; but the Greeks, and still more the Romans, who had profound respect for purple, used it of stone long ago. You have all heard of "porphyry" as among the most precious of the harder massive stones. The colour which gave it that noble name, as well as that which gives the flush to all the rosy granite of Egypt--yes, and to the rosiest summits of the Alps themselves--is still owing to the same substance--your humble oxide of iron. And last of all: A nobler colour than all these--the noblest colour ever seen on this earth--one which belongs to a strength greater than that of the Egyptian granite, and to a beauty greater than that of the sunset or the rose--is still mysteriously connected with the presence of this dark iron. I believe it is not ascertained on what the crimson of blood actually depends; but the colour is connected, of course, with its vitality, and that vitality with the existence of iron as one of its substantial elements. Is it not strange to find this stern and strong metal mingled so delicately in our human life, that we cannot even blush without its help? Think of it, my fair and gentle hearers; how terrible the alternative--sometimes you have actually no choice but to be brazen- faced, or iron-faced!