ment. To suppose that any would judge before they professed to know the conditions would seem to be absurd; on the other hand, to assume that the community does wait to know the conditions before it judges, is an assumption so large that I cannot accept it. Very few search out the conditions; most are anxious to sink those which oppose their preconceptions; yet none can be left out if a right judgment is to be formed. It is true, that many conditions must ever remain unknown to us, even in regard to the simplest things in nature: thus as to the wonderful action of gravity, whose law never fails us, we cannot say whether the bodies are acting truly at a distance, or by a physical line of force as a connecting link between them[1]. The great majority think the former is the case; Newton's judgment is for the latter[2]. But of the conditions which are within our reach, we should search out all; for in relation to those which remain unknown or unsuspected, we are in that very ignorance (regarding judgment) which it is our present object, first to make manifest, and then to remove.
One exercise of the mind, which largely influences the power and character of the judgment, is the habit of forming clear and precise ideas. If, after considering a subject in our ordinary manner, we return upon it with the special purpose of noticing the condition of our thoughts, we shall be astonished to find how little precise they remain. On recalling the phenomena relating to a matter of fact, the circumstances modifying them, the kind and amount of action presented, the real or probable result, we shall find that the first impressions are scarcely fit for the foundation of a judgment, and that the second thoughts will be best. For the acquirement of a good condition of mind in this respect, the thoughts should be trained to a habit of clear and precise formation, so that vivid and distinct impressions of the matter in hand, its circumstances and consequences, may remain.
Before we [proceed to consider any question involving physical principles, we should set out with clear ideas of the naturally possible and impossible. There are many subjects uniting more or less of the most sure and valuable investiga-
