Again, precisely the same circle of events takes place in numerous instances without any intervention of this additional factor of conscious will. We breathe mechanically, the muscles of the chest causing it to rise and fall like the waves of the ocean, without any deliberate intention of taking air into the lungs and exhaling it. Nay more, there are instances of what was at first accompanied by the sensation of conscious will, ceasing to be so when the molecular movements had made channels for themselves, as when a piano-player, who had learned his notes with difficulty, ends by playing a complicated piece automatically. The case of animals also raises another difficulty. Suppose a retriever dog sees his master shoot at and miss a hare: shall he obey the promptings of his animal instinct and give chase, or those of his higher moral nature which tell him that it is wrong to do so without the word of command? It is hard to see how this differs from the case of a man resisting or yielding to temptation; and how, if we assign conscious will to the man, we can deny it to the dog. Reasoning from these premises, some philosophers have come to the conclusion that man and all animals are but mechanical automata, cleverly constructed to work in a certain way fitting in with the equally preordained course of outward phenomena; and that the sensation of will is merely an illusion arising as a last refinement in the adjustment of the machinery. But here comes in that principle of duality or polarity, by which a proposition may be at once true and untrue, and two contradictory opposites exist together. No amount of philosophical reasoning can make us believe that we are altogether machines and not free agents; it runs off us like water from a duck’s back, and leaves us in presence of the intuitive conviction that to a great extent Man is man and master of his fate. If this be an illusion, why not everything—evidence of the senses, experiment, natural law, science, as well as morality and religion? To pursue this farther would lead us far astray into the misty realm of metaphysics, and I refer to it only as showing that the principle of the conservation of energy, standing as it does in apparent contradiction to our natural impressions, requires a fuller demonstration than the kindred principle of the indestructibility of matter. [Illustration]