Theological philosophy is the “explanation” of nature which the human mind first makes for itself. In order that it may give up this “explanation” some contrary evidence must oblige it to do so. It may see for instance, that phenomena can be predicted with a perfect exactness which is always confirmed by experience, or that man, under certain conditions, can modify them with certainty. Astronomy gives us an example of the former case. It studies phenomena which, it is true, are removed from our sphere of action. But, in return, it predicts them with a certainty of which the effect has been practically infallible in the long run. It is astronomy which has done most to discredit the religious and philosophical doctrine of final causes.[150] Not only has it proved that the universe is not disposed with reference to man, but it has shown the imperfections of our solar system. It has helped more than any other science to check the mental habit of seeking the mode of production of phenomena. Physics is far from allowing of a rational prevision which is comparable to that practised by astronomy. But, as a compensation, it shows how the knowledge of laws gives the power to cause phenomena to vary with certainty. This second way leads us no less surely than the first to the positive conception of nature. For example, Franklin destroyed the religious theory of thunder, even in the least cultivated intellects. The discovery of the means of directing lightning therefore had the same effect, in another way, as the exact prevision of the return of comets.[151] On the other hand the sciences of the inorganic world furnish the general positive method with some of its most powerful processes. Astronomy introduces observation and hypothesis into this method, Physics adds experimenting to it, and Chemistry the art of nomenclatures. The inductive method, which virtually consists in simple scientific observation, becomes, however, enriched and is developed, according as the phenomena in question become more complicated.