In maintaining it to be a law, however, he confuses the sense in which science uses this term and that which belongs to it in the sphere of ethics and politics. He says “It is an important element in the nature of law, that it is wholly mandatory. It commands, it neither solicits nor permits.” Now this is true enough of a moral or a criminal law, but it is entirely incorrect when applied to a so-called law of Nature. The latter is simply an expression of a certain general fact which we perceive in the order of the universe; and it takes the form, not of a mandate but of an affirmation. “Thou shalt not kill” here is the law of conscience and of citizenship: The law of Nature is such as that all matter attracts all other matter in direct proportion to its mass and in inverse proportion to the square of its distance. The real question is whether Homoeopathy is such a law as that of gravitation.
It is an inference from certain observed facts: Shall we state the inference by an affirmation, universal, exclusive, unchanging, that “likes are cured by likes,” or by a practical conclusion, admitting of qualification and exception “let likes be treated by likes?” Dr. Wells, and those who think with him, declare for the former alternative. I must follow Hahnemann himself in thinking the latter the utmost for which we have warrant. It requires a vast number of observations and experiments are we can formulate a law of Nature, while a rule of art can be deduced from a very few particulars its application being a speedy test of its validity. I cannot think we are justified in affirming that all morbid states are curable by their similars or better cured thus than by any other means: I can only feel borne out by the facts when I affirm that my practical wisdom lies in following the rule “let likes be treated by likes” as fully as I am able.