But let us approach the matter more closely. To physical science, one act is precisely the same as another; a mere matter of molecular movement or change. You raise your arm, you think with the energy and profundity of a Hegel; to the physicist it is all one and the same thing--a fresh distribution of matter and motion, muscular contraction, and rise and fall of the grey pulp called brain. A burglar shoots a policeman dead and the public headsman decapitates a criminal. To physical science, those two acts differ in no respect. They are exercises of muscular energy, expenditure of nervous power, the effecting of molecular change, and there the matter ends. But surely, you would urge, the scientist would discriminate between those two acts. Most assuredly. The one he would reprobate as immoral, and the other he would approve as lawful. But, be it carefully noted, he would do this, not as a scientist, but as a citizen respecting law and order and upholding good government based on morality and justice. As a moralist, then, but not as a scientist does he pass judgment, for there is no experimental science which deals with such matters. Physics concerns itself solely with what it can see and handle--nothing else. The actions, therefore, of right and wrong, justice and injustice, morality and immorality are simply unintelligible to it, just as unintelligible as they are to the most highly developed animal. It is the fully developed mind or intelligence alone which apprehends the sublime conception of duty, and the indefeasible claims which it has upon the allegiance of the will, and, in consequence, the scientist who denounces injustice and iniquity is no longer on the tripod of the professor, but in the rostrum of the ethical teacher. If I may say so, it supplies us with an admirable illustration of a quick-change performance. The same man performs a double part, and so adroitly is the change managed, that the performer himself is deceived into thinking that he is still the scientist, whereas he has become for the moment the moral professor. But he did not acquire that new teaching in the laboratory; he learnt it in the study.