* Emphasis: The repetition of "nous" emphasizes the fact that the action of washing is being performed by ourselves, as opposed to someone else. It reinforces the personal nature of the action.
* Intensification: The repetition creates a sense of intensity and urgency. It suggests that the act of washing is important and should be done thoroughly.
* Grammatical structure: In French, reflexive verbs often use the reflexive pronoun twice: once before the verb and once after it. This is a grammatical convention that emphasizes the reflexivity of the action.
In summary, the repetition of "nous" in "lavons-nous" is not simply redundant. It adds a layer of meaning and emphasis to the phrase, making it more impactful and evocative.