the amount of evidence so great, and special features are so numerous, that the thorough discussion of the problem in all its bearings will furnish employment for the most acute and comprehensive powers of analysis for an indefinite period; but there is no reason to believe that the subject is beyond our grasp, or that it is not a perfectly proper field for intellectual activity.
We may fairly ask, though, whether, after all this is granted, it pays to spend our time in speculation upon circumstantial evidence, when all our conclusions may possibly be wrong, when they can not possibly be true unless they are put into a general form, and when the presumption in their favor is only a probability at best. Would it not be wise for us to spend all our time in the observation of nature, rather than to devote our energies to the discussion of general problems?
In matters where we are called upon to act we must weigh the probabilities, and form the best judgment we can according to our evidence; but this is necessary because we must act in any case, and it is no reason for carrying scientific thought into similar fields. In life it is often wise to act against the probabilities, as when an old man denies himself to make provision for a prolonged life, which he has very little chance of enjoying; but it does not follow that it is wise to form a scientific conclusion against the probabilities, and, if the analogy of actual life will not justify this, how can it justify a scientific conclusion which is based upon probabilities in the absence of demonstrative evidence?
If science were a pure abstraction, standing by itself, this objection might have weight; but no part of the phenomenal world does stand by itself, and nothing in nature is so independent of human interests that broader knowledge does not conduce to wiser judgments and actions: nor is the past history of life a remote subject, bearing so slightly upon human interests that it may properly be left to occupy the time and energy of future generations.
It has the same importance to us as living things that the history of the human race has to us as human beings. The future history of our race will be a continuation of the one line as well as of the other, or, rather, one is included by the other. The end of the study of history is not the discovery of what has been in the past, but the discovery of general laws and causes that shall enable us to foresee what is to take place in the future; but this sort of historical knowledge, the wisdom of history, does not come from observation, but from reflection upon the inner relations, the causes and effects of phenomena—from a weighing of the probabilities between one interpretation and another; and the wisdom which leads us to accept and act upon these probable conclusions, as the best available basis for the guidance of conduct, equally requires us to accept, in the same way, the results of the study of our prehistoric life-history. Our conclusions may be wrong, but,