Emily Dickinson Lexicon

UN-LESS', conj. [Sax. onlesan, to loose or release.]

Except; that is, remove or dismiss the fact or thing stated in the sentence or clause which follows. “We can not thrive unless we are industrious and frugal.” The sense will be more obvious with the clauses of the sentence inverted. Unless, [remove this fact, suppose it not to exist,] we are industrious and frugal, we can not thrive. Unless then answers for a negation. If we are not industrious, we can not thrive.