In the first place, a PERMISSION ought to give way to a COMMAND: because a permission appears to be granted only in case there is no weightier objection than its being an exception to a positive precept, nor any preponderance in favour of an opposite determination. Consequently, as the writer to Herennius says, what is positively prescribed is more powerful than a bare permission. In the next place what is required to be done at a FIXED time should have the preference to what may be done at ANY time. From whence it follows that the PROHIBITIONS of a treaty are generally of more weight than its INJUNCTIONS: because the prohibitory power operates at ALL times. But it is not so with injunctions, unless an express time for their fulfilment is named, or they contain a tacit prohibition. Among those treaties, which, in the above named respects, are equal, the preference is given to such as are more particular, and approach nearer to the point in question. For where particulars are stated, the case is clearer, and requires fewer exceptions than general rules do.[51] Those prohibitions which have a penalty annexed to them, are of greater weight than those, which have not; and those with a greater penalty are enforced in preference to those that have a less. Those engagements also which are founded upon causes of less magnitude and importance ought to give way to those which have more laudable and useful objects in view. Lastly it is to be observed that a subsequent law or treaty always repeals a former. From what has been said an inference may be drawn in favour of sworn treaties or agreements that they ought to be taken in the most usual acceptation of the words, rejecting all implied limitations and exceptions, and such as are not immediately necessary to the subject. Consequently in a case, where a sworn treaty or engagement may happen to clash with another not enforced by the obligation of an oath, the preference ought to be given to the former. XXX. It is often asked whether in doubtful points, a contract should be deemed perfect, before the writings are made and delivered. We find in Appian's history of the Mithridatic war, that it was upon this very ground Murena objected to the convention between Sylla and Mithridates. However it appears plain, unless it has been settled to the contrary, that writing ought to be considered admissible as evidence of a contract, though not as part of the substance, otherwise it is usually expressed, as in the truce with Nabis, which was to be ratified from the day the terms were WRITTEN and DELIVERED to him.