Certainly an act of will is necessary in order to construct empirical concepts, formulæ, and rules (as indeed we know), an act of will which is not that of the will implied in every act of thought, but is a special and explicit act which, by manipulating representations and concepts, makes a _quid medium,_ which is neither representation nor concept, and although altogether irrational from the theoretical point of view, is of use in the economy of the spirit. But the law in its true meaning is a volitional act, which _assumes_ that primary volitional act whence are formed the pseudo-concepts or concepts of class _as already completed;_ precisely because it is the will which has for its _object_ a _class_ of objects. It is not possible to impose speaking according to the rule of the Greek language, or to melt platinum according to its chemical formula, before these rules have been laid down. And here appears very clearly the difference between those two kinds of spiritual products, which the imperative literary form, given to classes and rules, darkens and confuses. This difference can be recognized in concrete cases by means of a most simple expedient: if the rule (as we have already had occasion to prove) can be converted into a statement of class, then the law is inconvertible. "If you wish to melt platinum, heat it to 1780 degrees" is a proposition that is exactly equal to "platinum melts at 1780 degrees." But the law, "Let there be opened in every city a chemical laboratory where platinum is to be melted," is not to be converted from the imperative to the indicative, whatever efforts we make. [Sidenote: _Distinction of laws from practical principles._] If the volitional element be wanting to naturalistic laws, it is certainly present in other spiritual formations also denominated and considered as laws: but not that of _class,_ therefore neither are these laws. Such is the case with economic and moral law, and through them, with logical and æsthetic laws. The moral law says, "Will the universal"; that is to say, "Will the good, the useful, the true, the beautiful." Therefore (considered in reality and not in scientific theory, where it appears as the concept of itself) it is a volitional act. But this volitional act has the spirit itself for object, which is and exists, in so far as it wills and affirms itself; it has for object a form or a _universal,_ whereas laws have for object something material and at the same time not instantaneous, something more or less fixed, something _general:_ a _class,_ not an _idea._ Universal laws (that would better be called _principles_) are the Spirit or producer; true and proper laws are the special product of the spirit; therefore the first can certainly be called laws, but for an altogether different reason to the second. [Sidenote: _Laws and single acts._]