As to the more mathematical sciences, there will be no one to doubt but some of their principles must be admitted as infallible truth; for our minds are so constituted that they are incapable of resisting a fair presentation of mathematical demonstration. Now, there is scarcely any physical science that is not based more or less upon mathematical truth; and as to the facts in those sciences, some of them are so multiplied, and speak so uniformly the same language, that we doubt them no more than we do a mathematical demonstration. Other classes of facts are less decided; and in some cases they are so insulated as to be regarded as anomalies, to be set aside until better understood. The same grades of certainty exist in respect to inferences from the facts of science. Some theories are scarcely less doubtful than mathematics; others are as strong as probable reasoning can make them; and others are merely plausible. Hypotheses are still less to be trusted, though sometimes extremely probable.
Now, most of the physical sciences embrace facts, theories, and hypotheses, that range widely along the scale of probability, from decided demonstration to ingenious conjecture. It is easy, however, in general, to distinguish the demonstrated and the permanent from the conjectural and the fanciful; and when we bring the principles of any science into comparison with religion, it is chiefly the former that should be considered, although scientific hypothesis may sometimes be made to illustrate religious hypothesis. But, passing by all other sciences, it is my desire to present before you, on this occasion, the claims of geology, as having fundamental principles so well settled that they claim attention from the interpreter of the Bible. I ought, however, to remark, that there exists a strange jealousy of this science even among intelligent men; a suspicion that its votaries have jumped at strange and dangerous conclusions through the influence of hypothesis, and that in fact the whole science is little else but hypothesis, and that there is almost no agreement even among its ablest cultivators. It is indeed a comparatively recent science, and its remarkable developments have succeeded one another so rapidly, as to leave men in doubt whether it would not prove a dazzling meteor, instead of a steady and permanent luminary. When the men who are now in the full maturity of judgment and reason, (and whose favorable opinion I am, therefore, anxious above that of all others to secure,) when these were young, geology did not constitute a branch of finished education; and amid the pressure of the cares and duties of middle life, how few find the leisure, to say nothing of the disposition, carefully to investigate a new and extensive science! Even though younger men should be found standing forth as the advocates of geology, yet how natural for those more advanced to impute this to the ardor and love of novelty, characteristic of youth!