These are only a few examples of the points of physical science on which scepticism at this moment has batteries erected with which to assail spiritual religion. Will the minister but slightly familiar with the ground chosen by the enemy be able not only to silence his guns, but, as every able defender of the truth ought to do, to turn them against its foes? Surely it needs a professor of natural theology in our theological seminaries, (and if such chairs existed in our colleges they would be serviceable,) to teach those who expect to be officers in the sacramental host how to carry on the holy war. I do not see how much more time can be given to the natural sciences in our colleges than is usually done, without encroaching upon other indispensable branches. If, therefore, provision be not made for studying the religious bearings of these sciences in our theological seminaries, our youthful evangelists must go forth to their work without the ability to vindicate the cause of religion against the assaults of the sceptical naturalist. Would not, then, those wealthy and benevolent individuals be great public benefactors, who should endow professorships of natural religion in our schools of the prophets? But I must not pursue this subject farther. I commit my work to the public with no raised expectations of its welcome reception. I have a high opinion of the enlightened candor of, the educated classes of our country, especially those in the ministry. Yet I know that many prejudices exist against science in its connections with religion. And, therefore, my only hope of any measure of success in this effort rests upon the divine blessing. But if the work be not pleasing to Infinite Wisdom and Benevolence, why should I desire for it an ephemeral success among men? AMHERST COLLEGE, May 1, 1851. EXPLANATION OF THE FRONTISPIECE. This section of the earth's crust is intended to bring under the eye the leading features of geology. 1. _The relative Position of the Stratified and the Unstratified Rocks._ The unstratified rocks, viz., granite, sienite, porphyry, trap, and lava, are represented as lying beneath the stratified class, for the most part, yet piercing through them in the centre of the section, and by several dikes or veins, through which masses have been protruded to the surface. The unstratified class are all colored red, to indicate their igneous origin. Granite seems to have been first melted and protruded, and it continued to be pushed upward till the close of the secondary period of the stratified rocks, as is shown by the vein of granite on the section. Sienite and porphyry seem to have been next thrust up, from below the granite; next, the varieties of trap were protruded from beneath the porphyry; and last, the lava, which still continues to be poured out upon the surface from beneath all the rest. 2. _The Stratified Rocks._