universal this may be). Even the rules of corresponding phenomena
are only called laws of nature (e.g., the mechanical laws), when we
either know them really a priori, or (as in the case of chemical laws)
suppose that they would be known a priori from objective grounds if
our insight reached further. But in the case of merely subjective
practical principles, it is expressly made a condition that they rest,
not on objective, but on subjective conditions of choice, and hence
that they must always be represented as mere maxims, never as
practical laws. This second remark seems at first sight to be mere
verbal refinement, but it defines the terms of the most important
distinction which can come into consideration in practical
investigations.



IV. THEOREM II.



A rational being cannot regard his maxims as practical universal
laws, unless he conceives them as principles which determine the will,
not by their matter, but by their form only.

{BOOK_1|CHAPTER_1 ^paragraph 45}

By the matter of a practical principle I mean the object of the
will. This object is either the determining ground of the will or it
is not. In the former case the rule of the will is subjected to an
empirical condition (viz., the relation of the determining idea to the
feeling of pleasure and pain), consequently it can not be a