Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
IT is also important to note that the Law does not take into account exceptional circumstances; it is not based on conditions which rarely occur. Whatever the Law teaches, whether it be of an intellectual, a moral, or a practical character, is founded on that which is the rule and not on that which is the exception: it ignores the injury that might be caused to a single person through a certain maxim or a certain divine precept. For the Law is a divine institution, and [in order to understand its operation] we must consider how in Nature the various forces produce benefits which are general, but in some solitary cases they cause also injury. This is clear from what has been said by ourselves as well as by others. We must consequently not be surprised when we find that the object of the Law does not fully appear in every individual; there must naturally be people who are not perfected by the instruction of the Law, just as there are beings which do not receive from the specific forms in Nature all that they require. For all this comes from one God, is the result of one act; "they are all given from one shepherd" (Eccles. xii. 11). It is impossible to be otherwise; and we have already explained (chap. xv.) that that which is impossible always remains
impossible and never changes. From this consideration it also follows that the laws cannot like medicine vary according to the different conditions of persons and times; whilst the cure of a person depends on his particular constitution at the particular time, the divine guidance contained in the Law must be certain and general, although it may be effective in some cases and ineffective in others. If the Law depended on the varying conditions of man, it would be imperfect in its totality, each precept being left indefinite. For this reason it would not be right to make the fundamental principles of the Law dependent on a certain time or a certain place; on the contrary, the statutes and the judgments must be definite, unconditional and general, in accordance with the divine words: "As for the congregation, one ordinance shall be for you and for the stranger" (Num. xv. 15); they are intended, as has been stated before, for all persons and for all times.
After having Premised these introductory remarks I will now proceed to the exposition of that which I intended to explain