First, then, it came in the form of the _heliocentric theory of the planetary system_. We once thought the earth the center of the universe, and so firm that it can not be moved. But science shows that it moves about the sun, and spins unceasingly on its axis. Every one has heard of the terror of the sheep produced by this discovery, and the nearly tragic results to the bold scientist. But now we look back with wonder that there should have been any trouble at all. Would any Christian now consent to give up the grand conceptions of Nature and of God thus opened to the human mind--the idea of infinite space full of worlds, of which our earth is one, moving in silent harmony as in a mystic dance? Verily, this wolf has proved itself a harmless, nay, a very noble beast, and lies down in peace with the lambs. Next, it came in the shape of the _law of gravitation_, as sustentation of the cosmos by law and resident forces. The effect of this on religious thought was even more profound, though less visible on the surface, because only perceived by the most intelligent. It seemed at that time to remove God from the course of Nature. This was the real ground of the skepticism of the last century, and also the real motive of Voltaire’s ardent advocacy of Newton’s views before these were generally accepted in France. But now, who would give up this grand idea--this conception of law pervading infinite space--the same law which controls the falling of a stone guiding also the planetary orbs in their fiery courses? This is indeed the divine spheral music, inaudible but to the ear of science, accompanying the celestial dance. Next, it came in the form of the _antiquity of the earth_ and of the cosmos. The earth which we had fondly thought made specially for us about six thousand years ago; sun, moon, and stars, which we had vainly imagined shone only for our behoof--these, science tells us, existed and each performed its due course inconceivable ages before there was a man to till the ground or contemplate the heavens. Some of my readers may still remember the horror, the angry dispute which followed the promulgation of these facts. But now, who would consent to give up the noble conception of infinite time thus opened to the human mind and become forever the heritage of man? Next, it came in the form of the _antiquity of man_. It is probable, nay, certain, that man has inhabited the earth far longer than we had previously supposed we had warrant for believing. The controversy on this question and the dread of its result has indeed not yet entirely subsided. Some timid people still look askance at this wolf, but I think all intelligent people accept it and find it harmless.