But all this labor is probably a waste of time and of intellectual power. The attempt at turning sensation into thought only results in turning thought into sensation. It is an error that we only know what we perceive through the senses, or transform by the action of the mind. It is not true that we only know that of which we can form a sensible image. We know the existence of the soul as certainly as that of the body. We know the infinite and the eternal as well as we know the finite and temporal. We know substance, cause, immortal beauty, absolute truth, as surely as the flitting phenomena which pass within the sphere of sensational experience. These convictions belong, not to the sphere of sentiment and emotion, but to that of knowledge. It is because they show us realities and not imaginations, that they nerve the soul to such vast efforts in the sphere of morals, literature, and religion.
The arguments against the independent existence of the soul which Tyndall puts into the mouth of his Lucretian disciple are not difficult to answer. "You can form no picture of the soul," he says. No; and neither can we form a mental picture of love or hate, of right and wrong, or even of bodily pain and pleasure. "If localized in the body, the soul must have form." Must a pain, localized in the finger, have form? "When a leg is amputated, in which part does the soul reside?" We answer, that the soul resides in the body, with reduced power. Its instrument is less perfect than before—like a telescope which has lost a lens. "If consciousness is an essential attribute of the soul, where is the soul when consciousness ceases by the depression of the brain?" Is there any difficulty, we reply, in supposing that the soul may pass sometimes into a state of torpor, when its instrument is injured? A soul may sleep, and so be unconscious, without being dead. "The diseased brain may produce immorality: can the reason control it? If not, what is the use of the reason?" To this we answer that the soul may lose its power with a diseased body; but when furnished with another and better body, it will regain it. "If you regard the body only as an instrument, you will neglect to take care of it." Does the astronomer neglect to take care of his telescope?
These answers to the Lucretian may be far from complete; but they are at least as good as the objections. The soul, no doubt, depends on the body, and cannot do its work well when the body is out of order; but does that prove it to be the result of the body? If so, the same argument would prove the carpenter to be the result of his box of tools, and the organist to be the result of his organ. The organist draws sweet music from his instrument. But as his organ grows old, or is injured by the weather, or the pipes crack, and the pedals get out of order, the music becomes more and more imperfect. At last the instrument is wholly ruined, and the music wholly ceases. Is, then, the organist dead, or was he only the result of the organ? "Without phosphorus, no thought," say the materialists. True. So, "without the organ, no music." Just as in addition to the musical instrument we need a performer, so in addition to the brain we need a soul.
There are two worlds of knowledge,—the outward world, which is perceived through the senses, and which belongs to physical science, and the inward world, perceived by the nobler reason, and from which a celestial light streams in, irradiating the mind through all its powers. Religion and science are not opposed, though different; their spheres are different, though not to be divided. Each is supreme in its own region, but each needs the help of the other in order to do its own work well. Professor Tyndall claims freedom of discussion and inquiry for himself and his scientific brethren, and says he will oppose to the death any limitation of this liberty. He need not be anxious on this point. Religious faith has already fought this battle, and won for science as well as for itself perfect liberty of thought. The Protestant churches may say, "With a great sum obtained we this freedom." By the lives of its confessors and the blood of its martyrs has it secured for all men to-day equal rights of thought and speech. What neither Copernicus, Kepler, nor Galileo could do was accomplished by the courage of Martin Luther, John Calvin, John Knox, and Oliver Cromwell.
And now the freedom they obtained by such sacrifices we inherit and enjoy: "We are free-born." We may be thankful that in most countries to-day no repression nor dictation prevents any man from expressing his inmost thought. We are glad that the most rabid unbelief and extreme denial can be spoken calmly in the open day. This is one great discovery of modern times, that errors lose half their influence when openly uttered. We owe this discovery to the Reformation. The reformers made possible a toleration much larger than their own; unwittingly, while seeking freedom for their own thoughts, they won the same freedom for others, who went farther than they. They builded better than they knew.
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Professor Tyndall's address is tranquil yet earnest, modest, and manly. But its best result is, that it shows us the impotence of the method of sensation to explain the mystery of the universe. It has shown us clearly the limitations of "the understanding judging by sense"—shown that it sees our world clearly, but is blind to the other. It can tell every blade of grass, and name every mineral; but it stands helpless and hopeless before the problem of being. Science and religion may each say with the apostle, "We know in part and prophesy in part." Together and united, they may one day see and know the whole.