XIX. VIS INERTIÆ IN NATURE AND LIFE. IT happened to me, once, to be invited to visit one of the vaults filled with those large safes which are used in banks and elsewhere. I noticed the heavy steel doors by which they are closed and secured, and took hold of one of these doors and tried to move it. I had to exert a good deal of force, and even then I only succeeded in causing it to move quite slowly. But when I attempted to stop this motion, I found it equally difficult to do so. Though the heavy door was going very slowly, it required a considerable muscular effort to check its progress. I thus perceived that it takes as much power to stop such motion as it does to begin it. This is a simple illustration of what physical science has called the vis inertia, or inert force. Sir Isaac Newton defined "inertia, or the innate force of matter," as "the power of resistance by which every material body endeavors to persevere in its present state, whether of rest, or of motion in a straight line." "But a body," he adds, "exerts this force only when another force, acting on it, endeavors to change its condition." Newton also adds that this may be called "vis inertia, or force of inactivity," and that it really means the inactivity of the mass of matter. But if it means inactivity, how can it be called "a force"? Is not "inert force a contradiction in terms? It seems to be not force, but a power of retaining force. Inertia is the great storehouse of the forces of nature, and prevents their dissipation and loss. If it were not for this power of inertia, the order of the universe could not be maintained. For without such a provision we could not rely on the continuity of the powers of gravity, magnetism, chemical action; there would be no guarantee for the movements of the planets in their orbits, for the return of day and night, summer and winter, for the growth of plants, the life of animals. "Conservation of force" is, in the last analysis, this mysterious law of inertia. The same law which governed the motion of the heavy steel door of the safe retains the sun and the stars in their places. But this law of inertia, or "inert force," finds other applications and illustrations in the intellectual and moral world. There is a law of inertia in thought, which is the "conservation of intellectual force." It means that all real thought, all insight of truth, is a permanent possession, and cannot be lost. It may change its form, but it cannot be destroyed. Bryant says of truth that "the eternal years of God are hers." Emerson tells us that "One accent of the Holy Ghost The heedless world has never lost." We are forever saying that "truth is mighty, and must prevail." This is one great hope for mankind, that every new truth, when once recognized, must enter into the life of the world, and contribute to its progress. But let us remember that the same law which preserves truth once attained makes the difficulty in its first reception. Reformers are apt to be bitter against conservatives, and call them bigots because they resist so obstinately the new light. But the same inertia which makes it hard to move the steel door keeps it in motion after it has once begun to move. If truth were easy to receive, it would be easy to lose it again. This is a lesson which reformers are slow to learn; but they need it, in order to be patient and just to their opponents, and candid in their judgments. We must be willing to grant that the same love of truth which moves the reformer is the motive which refuses to yield easily or suddenly to his arguments. It is best that it should be so. We may have some favorite measure which seems to us to contain the secret of all progress. It is the movement the time demands. It is perhaps the abolition of slavery, or of war, or of intemperance; it is woman suffrage, free trade, civil service reform, a broader Christian faith, a rational Christianity. We cannot see why men do not accept our belief, and accept it now. We wish to have it embodied at once in the law of the land or in the creeds of the church. It seems so true and right and necessary that we think it intolerable not to have it at once received by mankind. It is the law of inertia which stands in our way, and that is a most useful and beneficent law. It means that a vast amount of effort must be made to convince and convert men, before you can embody truth in institutions and laws. It means that the people must be educated to believe in the reform, otherwise it is of no use to enact it as a law. Passing a vote will not answer. Contriving to get a bare ma jority will not answer. Politicians want to carry the next election, and to carry it by any means, good or bad. But reformers have a much more difficult and important work. It is to change the convictions of the people, so that when the reform arrives it may come to stay. The same vis inertia which resisted it will then operate to maintain it. Slavery and its evils were discussed for thirty years, and then those evils had to be still more fully shown by the great rebellion and secession, before the people of the United States could be educated to the point of abolishing that pernicious institution. How often during those weary years the hearts of the antislavery reformers were chilled by dull opposition, |