But it would be unjust and unphilosophical to condemn the modern theory of Geologists because of their past errors. We must judge of this science, not according to what it once was in the feebleness of its infancy, but according to what it now is in the growing strength of its mature years. It seems to be in the nature of things that groundless speculations and wild conjectures go before, and sober Science follows in their wake. The visionary dreams of the Alchemist led the way to the science of Chemistry, and the idle fancies of the Astrologist have given place to the marvellous discoveries of Astronomy. So, too, amidst the confused mass of conflicting arguments and opinions, by which the phenomena of Geology were for a long time enveloped and obscured, the seeds of a new science were slowly germinating. New facts were eagerly sought after to support or to impugn the favorite theory of the hour; and though theory after theory passed away, yet the facts remained. In course of time this accumulation of facts became broad and deep and solid enough to form a sound basis for inductive reasoning; and thus almost within our own days Geology may be fairly said to have assumed the rank and dignity of a science. During the last quarter of a century it has been studied with a more ardent enthusiasm than, perhaps, any other science in England, in France, in Germany, and in America. It has been studied, too, upon better principles than before: less attention has been paid to the building up of theories, and far more pains and labor have been expended on the careful investigation of natural phenomena. There are still, no doubt, different schools of Geologists which are divided among themselves as regards many important details of theory; but there are some general conclusions upon which all Geologists are substantially agreed, and which, they assure us, are established by evidence that is absolutely irresistible. It is to these conclusions we wish to invite the attention of our readers; for they bear very closely on the question of the Antiquity of the Earth.