Usage notes

* (sense) Compare with weaker auxiliary verb (should), indicating a strong probability of the predicate's execution. * (sense) Compare with weaker auxiliary verb (should), indicating mere intent for the predicate's execution; and stronger auxiliary verb (will), indicating that the negative consequence will be unusually severe. * The past tense of "must" is also "must"; however, this usage is almost always literary (see Fritz Leiber quotation above). The past sense is usually conveyed by (had to). It is possible to use (be bound to) for the past also. For this reason, (have to) and (be bound to) are also used as alternatives to (must) in the present and future. * The principal verb, if easily supplied, may be omitted. In modern usage this is mainly literary (see Housman and Tolkien quotations above). * (term) is unusual in its negation. (term) still expresses a definite certainty or requirement, with the predicate negated. (term), on the other hand, is negated in the usual manner. Compare: :: You must not' read that book. (''It '''is''' necessary that you '''not read that book. ) :: You need not' read that book. (''It '''is not necessary that you read that book. ) * The second person singular no longer adds "-est" (as it did in Old English).