It can hardly be doubted, by the geologist, that nearly every part of the earth's crust, and its interior too, have been some time or other in a melted state. Now, as the metals and their ores are usually heavier than other rocks, we should expect that they would have accumulated at the centre of the globe, and have been enveloped by the rocks so as to have been forever inaccessible to man. And the very great weight of the central parts of the earth--almost twice that of granite--leads naturally to the conclusion that the heavier metals may be accumulated there, though this is by no means a certain conclusion; since at the depth of thirty-four miles air would be so condensed by the pressure of the superincumbent mass as to be as heavy as water; water at the depth of three hundred and sixty-two miles would become as heavy as quick-silver; and at the centre steel would be compressed into one fourth, and stone into one eighth, of its bulk at the surface. Still it is most probable that the materials naturally the heaviest would first seek the centre. And yet, by means of sublimation, and expansion by internal heat, or the segregating power of galvanic action, or of some other agents, enough of the metals is protruded towards the surface, and diffused through the rocks in beds, or veins, so as to be accessible to human industry. Here, then, we find divine benevolence, apparently in opposition to gravity, providing for human comfort. I have said that these metals were accessible to human industry. And it does require a great deal of labor, and calls into exercise man's highest ingenuity to obtain them. They might have been spread in immense masses over the surface; they might all have been reduced to a metallic state in the great furnace, which we have reason to suppose is always in blast, within the earth. But then there would have been no requisition upon the exertion and energy of man. And to have these called into exercise is an object of greater importance to society than to supply it with the metals. God, therefore, has so distributed the ores as to stimulate man to explore and reduce them, while he has placed so many difficulties in the way as to demand much mental and physical effort for their removal. Man now, therefore, receives a double benefit. While the metals themselves are of immense service, the discipline of body and mind requisite for obtaining them is of still greater value. This is the combined result of infinite wisdom and benevolence.