Of all subjects, the simple sciences of physics and chemistry, are at the present time, apparently making the most rapid advance, and the chief reasons for this probably are, 1st. they treat of facts and principles which can be verified, and 2nd. because the more complex sciences, together with the arts and manufactures based upon them, can only improve in proportion as they are developed. All the essentially human subjects, such as sociology, politics, morality, religious worship, &c., are in this position, and are probably results partly of the operation of the great principles of nature acting through the body and mind of man.
The chief method of discovering new truth is that of observation, experiment, and study, and further mental treatment of the results. The most systematic methods also of evolving new truths are those employed by scientific men in making discoveries, and when any person arrives at a new idea, he usually (either consciously or unconsciously) employs them.
The acquisition of new knowledge must of necessity precede its diffusion. Immediately a new truth, especially an important one, is discovered, its influence begins to permeate the existing mass of knowledge in various directions, causing us to view many of our old ideas in a new aspect; giving rise also by comparison and inference, and by processes of combination, permutation and analysis of ideas, to a multitude of other new truths, usually less important ones, which themselves also affect previous knowledge in similar ways,
and by analogous treatment give rise to additional new conceptions.
But although we evolve truthful new conceptions from previous ones by these purely mental methods, there is a limit to the number capable of being evolved from a limited stock of ideas, because the number of combinations and permutations of such a stock, though usually large, are themselves limited. The number however is large in proportion to the degree of essential importance of the ideas, and is greatest when we employ those of the fundamental principles of nature, already referred to; for instance a greater number of new ideas have been evolved by means of appropriate mental processes from the law of gravitation and from that of electro-magnetism than from any minor truth in science. Persons therefore who are the least familiar with great demonstrable principles are usually the least able to conceive new truthful ideas of intrinsic importance, or to draw new verifiable inferences of much theoretical value.
Every inventor and student knows that he continually requires new materials of thought, and if he does not obtain them, an obstacle, like a wall of adamant, rises before his mind in all directions, and prevents his forming new ideas. That also which is true of each individual is true of the collection of individuals, mankind; if new truths are not obtained, the thoughts of men flow in circles, and mental progress ceases. The mental characteristics of sequestered communities in remote isolated districts, are examples of this
fact. The influence of printing, railways, telegraphs, postal communication and other scientific developments, in aiding mental progress, afford other illustrations. A multitude of facts of this kind, and many others, leads us to the conclusion that each new idea requires a cause to produce it, and that human knowledge is subject to the great law of causation; also that the creation of an idea out of nothing would be a miracle, a phenomenon without a cause. Our present knowledge was not created by us, but was originated by previous knowledge and experience, including of course inherited impressions. Even in what is termed the "noblest effort of the mind," an act of reasoning or inference, we do not create an idea, but only render explicit in a new form of words, ideas already implicitly contained in the words of the propositions employed, as may easily be rendered manifest by mechanical means in Jevons's "Logical Machine;" a proper inference never contains more than its data. In the so-called "creation" of ideas by the imagination also, the new ideas are evolved from old ones, and rendered explicit by mental processes of analysis, combination, permutation, &c. Our scientific inventions also, being mental conceptions, an unlimited number of them cannot be made by means of a limited stock of old knowledge. It was in consequence of this limit, viz., the impossibility of actually creating ideas out of nothing, that human knowledge was not more advanced by metaphysical speculations until science with its experiments and
observations came to its assistance. These various facts prove the statement made in the Preface of this book, that present knowledge only enables mankind to maintain its present state.
Not only the mental, but also the physical advance of mankind is essentially dependent upon the discovery of new truths. Men's physical actions are determined not alone by their inherited and acquired tendencies and the influence of external nature upon them, but also by their ideas; as a man thinks, so also to a large extent does he act. Nations who do not adopt new ideas do not either mentally or physically advance, but change only so far as their immediate surroundings change; the Chinese are a remarkable example of this; even the tendencies which men inherit, were largely produced in their ancestors by the influence of ideas. The great fact of the essential dependence of human progress upon new knowledge, is a truth, the importance of which to man cannot be over-estimated, and is one which statesmen, ministers of religion, and philanthropists should seriously study.
Much of the apparent advance of this nation however is not real. The great bulk of our newly published knowledge, even that which is scientific, and considered by the public to be new, consists, not of new truths, but of old ones dressed in new forms of expression:—