μία χελιδὼν ἔαρ οὐ ποιεῖ

Etymology
lit. 'one swallow does not make a spring'. A remark found in 's ' (1098a18: “one swallow does not a summer make, nor one fine day; similarly one day or brief time of happiness does not make a person entirely happy”), itself inspired by the fable ' by.

Proverb

 * 1) one swallow does not a summer make