〜べし / 〜べからず (classical should / must not)
N1 grammar: classical auxiliary べし expressing obligation/certainty, and its negative form べからず (must not). Appears in laws, school rules, mottos, and literary contexts.
〜べし / 〜べからず
Formality Level: Archaic / Literary — laws, school rules, mottos, formal declarations, literary prose
Classical Origin: べし is one of the most important auxiliary verbs in classical Japanese (文語). It appears throughout the Manyoshu, the Kokinwakashu, Heian-period prose, medieval warrior codes, and Edo-period legal documents. べし derives from the adjective べき (beki) which itself comes from Old Japanese be-si expressing appropriateness, obligation, or strong probability. Its negative form べからず (from べから + ず, classical negative auxiliary) expresses categorical prohibition.
In modern Japanese, べし and べからず appear primarily in:
- Laws and regulations (especially older texts and mottos)
- School rules posted on walls
- Moral maxims and life principles (motto style)
- Classical literature
- Formal declarative statements for rhetorical effect
Structure
| Form | Usage |
|---|---|
| Verb (dictionary form) + べし | 学ぶべし |
| Verb (dictionary form) + べからず | 入るべからず |
| Suru-verb: する → すべし / すべからず | 努力すべし |
| Note: する + べし often contracts to すべし |
Meaning
〜べし: "Should / Must / Ought to / Shall" — obligation, strong recommendation, or in some classical contexts, strong probability/certainty.
〜べからず: "Must not / Shall not" — categorical prohibition.
Example Sentences — 〜べし
| Japanese | English |
|---|---|
| 武士は主君のために命を捨つるべし。 | A samurai should be prepared to give his life for his lord. (classical warrior code) |
| 人は常に誠実であるべし。 | A person should always be sincere. (moral maxim) |
| 学者たる者、学問に私情を挟むべからず。 | One who would be a scholar must not allow personal feelings to intrude upon scholarship. (moral declaration) |
| 関係者以外立入るべからず。 | Unauthorised personnel must not enter. (sign; modern usage) |
| 困難を前にして怯むべからず。前進すべし。 | Do not flinch before hardship. Press forward. (motivational motto) |
| 斯くあるべき政治の姿を、われわれは求め続けなければならない。 | We must continue to seek the form that politics ought to take. (formal essay) |
Comparison with N2 Equivalent
| Pattern | Register | Meaning | Key Difference |
|---|---|---|---|
| 〜べし/〜べからず | Archaic/literary | Classical obligation / prohibition | Categorical; impersonal; formal declaration |
| 〜べきだ/〜べきではない | Semi-formal | Should / Should not | Modern equivalent; more personal and neutral in tone |
| 〜なければならない | All registers | Must / Have to | Personal obligation; cannot express general categorical maxims as naturally |
Where These Appear Today
- Legal texts: Older versions of the Civil Code and criminal statutes contain べし and べからず extensively, though modern revisions have replaced many with べきものとする.
- School and dojo rules: 廊下を走るべからず。禮儀を忘るべからず。
- Corporate mottos and business philosophy statements: 顧客を第一とすべし。
- Literary fiction: Characters quoting or invoking classical codes; narrators using classical style for formal distance.
- Proverbs and inspirational quotes: Often attributed to historical figures (Miyamoto Musashi's Gorin no Sho uses べし extensively).
When NOT to Use
- Do not use in ordinary modern conversational or formal speech: べし and べからず sound archaic/theatrical in normal spoken or even formal written Japanese. Use 〜べきだ/〜べきではない.
- Do not use べからず for personal, hedged advice: 〜べからず is a categorical prohibition (a rule posted for all), not a personal recommendation.
- Note the する→すべし contraction: This is standard and must be memorised. ×するべし is not incorrect but すべし is the standard literary form.