A third note of the scientific mind is practicality of view. The highest reverence for truth is not inconsistent with a desire to put truth to practical uses. Nature is the supreme teacher, and yet, from a certain point of view, Nature may be said to exist for us, not we for Nature. We lay hold of her phenomena with a masterful grasp, and read laws into them, reserving to ourselves the right to read ever wider and higher laws as our knowledge widens. And when our minds are in free and unrestrained movement, and are being built up in symmetry and strength by what they absorb in the study of external things, we feel that the highest work of which we can form any conception is being accomplished. There are scientific workers whose whole ambition seems to be to form a kind of hortus siccus of observations and opinions, and whose own minds are but little transformed by the knowledge that passes through them. These lack the true scientific spirit, though their work may at times have its uses. They lack the joy of growth, and never realize the sense, at once of liberty and power, which those possess who look upon nature, not as a mere curiosity-shop or museum, but as a vast domain providing all that is necessary for the exercise, aliment, and discipline of the human mind.
The truly scientific spirit, we may lastly say, is essentially inductive. It feels its way into truth by slow degrees. If facts are at all accessible, it does not care to depend on hypotheses; and it is always ready to accept the yoke of facts—never tries to put a yoke on facts. In this respect it differs greatly from the disposition shown by many radical thinkers of to-day, who, having thrown overboard their former theological opinions, are none the less governed in their daily thinkings by old theological methods. Such confidence have these persons in their argumentative that they never seem to care to freshen their thought with new knowledge. Such and such are the cardinal principles in which they believe, and from these they are prepared to draw an ever-lengthening chain of conclusions, all, as they hold, of absolute certainty because the starting-point was, in their opinion, indubitably true. No man, however, who has a glimmering of the scientific spirit cares to follow this kind of dead-reckoning. "He to whom the Eternal Word has spoken," says a famous mediæval sage, "is set free from many opinions." So he, we may say, to whom Nature has spoken in intimate tones, who knows what it is to have studied Nature patiently and faithfully, is freed from all bondage to mere opinions by his supreme attachment to truth. His great interest lies in knowing what is, not what, according to somebody's way of looking at things, ought to be.
We may know the man, therefore, whose habits of thought are scientific by his abiding faith in the teachings of Nature; by his unshaken conviction that the uniformities we see in the occurrence of phenomena are but hints of the universal constancy of natural law; by his interest in all that can be brought under law, and lack of interest in all alleged lawless and abnormal manifestations; by his recognition of the inaccessibility of absolute truth, and his willingness to make the best of provisional theories and symbols; by his freedom from pedantry and dilettanteism; by his reverence for human nature; by his constant desire for the verification of opinions, and his consequent freedom from all infatuation, whether for the theories of others or for his own. He is a man whose moderation is known to all men, whose patience seems to have been learned from Nature herself, whose thought moves from year to year in larger circles, and whose character bears witness to the liberal and elevated character of his daily occupations. Do all men of science, all professors of philosophy, conform fully