Grammar › N1 · 10 Obligation and prohibition

〜べし: should; must (classical)

N1 · 10 Obligation and prohibition

Classical auxiliary meaning "should", "must" or "is sure to".

Dictionary form + べし. Modern form: べき (べきだ). Negative: べからず ("must not"), seen on signs. する → すべし. Archaic, written, mottos and period drama.

Examples

学生がくせいは学問がくもんに励はげむべし。

Students should devote themselves to study.

この先さき、入はいるべからず。

Do not enter beyond this point.