All the facts which it is possible for man to gather in a lifetime, added to all that are gathered by generation after generation, are but illustrations of a few principles. Modern teaching deals almost wholly with facts; it requires children, from the time they enter school until they are graduated, to heap together facts. Process is the great theme in mathematics; facts, facts, facts, are the things sought for in the whole realm of natural science. History is but the study of still more facts, and where generalizations or classifications are made, they are theories formulated from the facts gathered. But man is never able to collect all the facts; he is never sure that his conclusions have reached absolute truth. The truth of the matter is, the classifications thus formed are only partially correct, and the discovery of a few more facts overthrows the finespun theories of the best of scientists. It is thus constantly in astronomy, in botany, in zoology, and in biology. Because of new discoveries, the physician of yesterday is wholly wrong in the eyes of the physician of to-day. To-morrow the bright light of to-day will be superseded by some other luminary. This is the result of inductive reasoning based on sense perception. This thought is well expressed by Hinsdale, who says: “We observe and register phenomena, classify facts, deduce conclusions and laws, and build up systems; but in science and philosophy we return to the subject again and again; we seek to verify our facts and test our conclusions, and when we have finished, we are not sure, save in a limited sphere, of our results. Some of the best-known sciences have been largely reorganized within the last few years. We have the ‘new chemistry,’ the ‘new astronomy,’ the ‘new political economy,’ and even the ‘new mathematics.’ Particularly in the field of human conduct, where man’s will is the governing faculty, we are often uncertain of our way and sometimes are wholly lost.”[188] [Sidenote: Sense perception often incorrect] The shifting foundation upon which such knowledge rests is well illustrated by the tests which the human being is able to make with the organs of sense. Water of 98° is hot to the hand that has been accustomed to a temperature of 45°, but cool to the hand which is just taken from water of 112°. An orange is sweet to the man who has been eating a stronger acid, but sour to the palate accustomed to sugar. The eye which has been used in a dimly lighted room is dazzled by the noonday glare, and judging of the size of a star by sight we would not conceive it to be a sun. The knowledge gained by the senses is only partially true,—it is not absolute truth; and the scientific theories propounded by minds which have reasoned from these inaccurate data can not fail to fall short of absolute truth. It may be _knowledge_; it is not _wisdom_. [Sidenote: Faith is substance, not theory]