say, then, that there is a probability of life where the conditions of life exist, we mean nothing more, than that it is likely that a creative intelligence will, in similar circumstances, act similarly. We find that it is the usual plan of the Divine procedure to stock with living beings, regions which present the required conditions of life; and when we discover in any unknown region these conditions, we draw the probable inference that there are living beings.
The purely astronomical argument is one founded simply on the estimation of probabilities, and is independent of any genetic theories regarding the introduction of life The theist and the atheist can alike weigh this probability. The principle of analogy holds, whether we admit a necessary or an intelligent cause. But it is plain that the doctrine of the plurality of worlds, when argued on astronomical grounds, can never transcend the region of probability. To dogmatise is wholly to misapprehend the nature of the argument. The dogmatic tone frequently displayed in discussions of this subject grates harshly on the logical ear.
If we argue that, from the character of God, we must infer that the planets are inhabited, the ground is entirely changed, and astronomy given up. If the necessity can be established from the known attributes of God, there is no need of appealing to the analogical probability furnished by astronomy. But
