Attempts at a more scientific form of explanation have had their origin in the special branches of history (of languages, religion, law). By the separate study of the succession of facts of a single species, specialists have been enabled to ascertain the regular recurrence of the same successions of facts, and these results have been expressed in formulæ which are sometimes called laws (for example, the law of the tonic accent); these are never more than empirical laws which merely indicate successions of facts without explaining them, for they do not reveal the efficient cause. But specialists, influenced by a natural metaphor, and struck by the regularity of these successions, have regarded the evolution of usages (of a word, a rite, a dogma, a rule of law), as if it were an organic development analogous to the growth of a plant; we hear of the "life of words," of the "death of dogmas," of the "growth of myths." Then, in forgetfulness of the fact that all these things are pure abstractions, it has been tacitly assumed that there is a force inhering in the word, the rite, the rule, which produces its evolution. This is the theory of the development (_Entwickelung_) of usages and institutions; it was started in Germany by the "historical" school, and has dominated all the special branches of history. The history of languages alone has succeeded in shaking off its influence.[212] Just as usages have been treated as if they were existences possessing a separate life of their own, so the succession of individuals composing the various bodies within a society (royalty, church, senate, parliament) has been personified by the attribution to it of a will, which is treated as an active cause. A world of imaginary beings has thus been created behind the historical facts, and has replaced Providence in the explanation of them. For our defence against this deceptive mythology a single rule will suffice: Never seek the causes of an historical fact without having first expressed it concretely in terms of acting and thinking individuals. If abstractions are used, every metaphor must be avoided which would make them play the part of living beings.