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phenomena, as to be sure of the elements present, and sure, therefore, of the effects that may be expected. We do not know exactly how far one wood differs from another, one metal from another, one element, so called, from itself at a former period. Much less do we know all the circumstances which affect the complex problems of life, which influence the growth of a tree, which are concerned in the health of a man, in the welfare of a community. We here, therefore, advance from one case to another along uncertain links of likeness, not knowing positively whether the agreement covers the essential points of the two cases or not. The various degrees of likeness are identity, sameness, resemblance, analogy.

In induction, by which from several examples we infer a general principle, we are proceeding on a resemblance more or less obscure, hence more or less uncertain. Different cases stand on their own independent merits, and the probability in each is in proportion to the certainty with which the agreement in the example covers the force or forces involved in the causation under consideration. That all magnets attract iron, is a conclusion on which we rest with entire conviction, having by such uniform observation traced this result to this cause. Yet it is not an impossibility, that some new substance or combination of substances should exhibit the other properties of a magnet with the omission of this. We cannot say, how new conditions of action may modify the force termed magnetism.

Now, by far the larger part of the reasoning of natural science and of every-day-life is of this character, creeping from resemblance to resemblance, and unable to affirm of its best conclusions, that they are demonstrative. To this reasoning, the syllogism is not applicable, since the premises as premises are partial, and do not contain the law in its full breadth which is to be evolved from them. This philosophy