might possibly elucidate the subject from a different angle. The failure of the opinion in actually finding such an angle does not matter, more important is the open-mindedness which the free thinking man should constantly maintain. We must have as many opinions as possible to select from, true or false, or only partly so, and use our critical selective sense. The keeping alive of this critical selective sense is of the highest moment in man's rational life activity. In the rational equipment of the human mind it is of the utmost consequence to keep the edge of the critical sense bright and keen. In the course of examination of some new opinion which may afterwards be rejected some new sidelights may appear which may give a deeper insight into the nature of the subject, whether it be of a theoretical or practical character; some new views and modes of thought, new methods may be suggested which in their turn may result in the evolvement of new principles and important laws.
In the general history of science and in the history of each individual investigation we find this freedom of thought and critical sense ceaselessly at work. Rarely, if ever, do we strike in science the truth at a flash. We usually pass through a series of hypotheses, theories, speculations, and experimentations, often false or defective. Ever new lines of thought are struck out and new ways of experimentation are undertaken only to be rejected again and again. They who have undertaken a series of experiments on any subject realize the amount of work requisite before even the preliminaries may be started well under way. There must go on a ceaseless selection, an active criticism which is merciless to itself, ever hostile to routine, ever awake to new points of view and better methods of work, ever welcoming a different, but truer and better way of handling and treating the facts, observations, and experiments, ever ready to modify and change the course of the work, now in one place, now in another, ever retracing the steps of the research now in one way, now in another, until some satisfactory and unitary point of view is gained. And still with all that labor one must always be ready to abandon the whole line as false and start on a new track, ever revising his work, ever criticizing each step in advance, ever doubtful, looking at the work as if it might be on the false track, allowing for error, alive to new facts which may contradict the methods of observation and experimentation or the apparently established facts, rejecting hypothesis and theories which are attractive, or which have become endeared to the heart of the investigator, either because they are his
