Proverb: En boca cerrada no entran moscas

En boca cerrada no entran moscas is the Spanish way of saying "silence is golden". Literally, it means "flies don't enter a closed mouth". The proverb is short, sharp, and built on three grammatical features that Spanish uses everywhere: a fronted prepositional phrase, a past participle used as an adjective, and a verb that agrees with a subject placed after it, not before. Once you can see those three tricks, you can parse half of Spanish literature.

This page walks through each word, explains why the subject moscas sits at the end, and compares the proverb with a few other sayings about silence and speech.

The text

En boca cerrada no entran moscas.

Six words. No verbs to conjugate. No articles. Just a vivid image about keeping your mouth shut.

Grammar in action

Word by word

• En: preposition of location, "in".
• boca: feminine noun meaning "mouth". No article — typical of proverbs.
• cerrada: past participle of cerrar ("to close"), used as an adjective. Feminine singular, agreeing with boca.
• no: negation, modifying entran.
• entran: third-person plural present indicative of entrar. Regular -ar verb.
• moscas: feminine plural noun meaning "flies".

Literal reading: "Into a closed mouth, flies do not enter." The meaning is proverbial: if you keep quiet, you won't say anything foolish.

Past participle as adjective

Cerrada looks like a verb form, and in fact it is — the past participle of cerrar. But here it is used as an adjective describing the noun boca. Past participles are endlessly recyclable this way:

• una puerta abierta — an open door
• un libro escrito a mano — a handwritten book
• la comida preparada — the prepared food

When used as adjectives, past participles agree in gender and number with the noun they modify. Cerrada is feminine singular because boca is feminine singular. If the noun were bocas, it would become cerradas.

The fronted prepositional phrase

In neutral Spanish word order, a sentence about flies entering a mouth would start with the subject: Las moscas no entran en una boca cerrada ("Flies don't enter a closed mouth"). But the proverb puts the prepositional phrase en boca cerrada at the front of the sentence. This is topicalization — the phrase is lifted to the beginning to signal that it is what the proverb is about.

• Neutral: [subject] Las moscas
  • [verb] no entran
    • [place] en boca cerrada.
• Proverbial: [place] En boca cerrada
  • [verb] no entran
    • [subject] moscas.

Spanish lets you reorder major constituents much more freely than English does. Once the prepositional phrase is fronted, the subject naturally slips to the end.

Subject after the verb

Notice that moscas comes after entran. In English, the subject almost always comes before the verb: "flies don't enter". In Spanish, the subject can sit on either side of the verb, and it very often follows when:

• the verb is intransitive (like entrar, venir, salir);
• a prepositional phrase or adverb has been fronted;
• the subject is indefinite or new information.

All three conditions apply here: entrar is intransitive, the prepositional phrase en boca cerrada is fronted, and moscas is indefinite (no article). The result is the inverted order that proverbs love.

Why no article before boca and moscas?

English speakers expect "a closed mouth" and "the flies". The Spanish proverb uses neither. This is another proverbial reflex: bare nouns are common in proverbs, slogans, and newspaper headlines when the nouns are generic or abstract.

Compare:

• Agua que no has de beber, déjala correr. (No article before agua.)
• Perro que ladra no muerde. (No article before perro.)
• Hombre prevenido vale por dos. (No article before hombre.)

In everyday speech, the articles usually come back. But in proverbs, the bare noun is part of what makes them sound old and wise.

The impersonal feel

Although entran moscas has a grammatical subject (moscas), the proverb feels impersonal. You are not pointing to specific flies; you are stating a general fact. Spanish achieves this impersonal flavor through several grammatical moves at once:

• Third-person plural verb with an indefinite subject (entran moscas).
• No article before the subject noun.
• The fronted prepositional phrase.

Together they produce the same kind of generic claim you would make in English with "flies don't enter" or "one doesn't catch flies that way". The Spanish version is more compact because the language tolerates verbless and article-less constructions more easily.

Related proverbs about speech and silence

El que mucho habla, mucho yerra

Literally "He who talks a lot, errs a lot". Grammar highlight: el que is the free relative, mucho is an adverb modifying both verbs, yerra is the present of errar (an e → ye stem-changing verb).

Al buen callar llaman Sancho

Literally "They call good silence Sancho". A classic Cervantes-era saying meaning that keeping quiet is a noble act. Grammar highlight: the impersonal third-person plural llaman ("they call"), which works like English "they say…". Sancho is a proper name used generically for a respectable person.

Por la boca muere el pez

Literally "The fish dies through its mouth". Meaning: you can get yourself in trouble by talking too much. Another fronted prepositional phrase (por la boca), another inverted subject (el pez at the end).

Hablando del rey de Roma, por la puerta asoma

Literally "Speaking of the king of Rome, in through the door he appears". Spanish for "speak of the devil". The gerund hablando stands alone as a discourse marker, and asoma takes no explicit subject — it is understood from context.

When to use this proverb

• Advising someone to stay silent rather than say something risky.
• Defending your own silence in a meeting or conversation.
• Commenting on the wisdom of holding back.

It is used all over Latin America, often shortened to just En boca cerrada… with the rest left to the listener.

Key takeaways

For more on the grammar behind this proverb, see word order flexibility, subject position, past participle as adjective, and the impersonal se.