and perform miracles in art.  He is the celestial limner who shall preserve the authentic faces of every generation from now until the world is no more.  He holds the mirror up to Nature, paralyzes the fleeting phantom, by chemical subtilty, on the burnished plate,—­and there it is fixed forever.  He prepares the optical illusion of the stereoscope, so that through tiny windows we may look as into fairy-land and find sections of this magnificent world modelled in miniature.

Once men imagined the earth to be a flat and limited tract.  Now they realize that it is a ponderous ball floating in infinite ether.  Once they thought the sky was a solid blue concave, studded with blazing points, an empire of fate, the gold-and-azure floor of the abode of gods and spirits.  Now all that is dissolved away; the wandering planets become at will broad disks, like sisters of the moon; and countless millions of stars are now mirrored in the same retina with which the Magi saw the few thousands of the firmament that were visible from the plains of Chaldea.

Once men were aware of nothing in the earth beneath its hills and valleys and teeming soil.  Now they walk consciously over the ruins of old worlds; they can decipher the strange characters and read the strange history graven on these gigantic tablets.  The stony veil is rent, and they can look inimitable periods back, and see the curious animals which then moved up and down in the earth.

Once a glass bubble was a wonder for magnifying power.  Now the lenses of the microscope bring an inverted universe to light.  Men can look into a drop and discover an ocean crowded with millions of living creatures, monsters untypified in the visible world, playing about as in a great deep.

Once a Roman emperor prized a mysterious jewel because it brought the gladiators contending in the arena closer to the imperial canopy.  Now observatories, with their revolving domes, crown the heights at every centre of civilization, and the mighty telescope, poised on exquisite mechanism, turns infinite space into a Coliseum, brings its invisible luminaries close to the astronomer’s seat, and reveals the harmonies and splendors of those distant works of God.

Once the supposed elements were fire, and water, and earth, and air; once the amber was unique in its peculiar property, and the loadstone in its singular power.  Now chemistry holds in solution the elements and secrets of creation; now electricity would seem to be the veil which hangs before the soul; now the magnetic needle, true to the loadstar, trembles on the sea, to make the mariner brave and the haven sure.

We have by no means exhausted the wonders that have accumulated upon man, in being accumulated by man.  Their enumeration would be almost endless.  But we leave all to mention one, with which there is nothing of old time to compare.  It had no beginning then,—­not even a germ.  It is the peculiar leap and development of the age in which we live.  Many things have combined to bring it to pass.