A cuckoo, a swallow… and spring

This idiom is used to say that because one good thing has happened, it is not, therefore, certain that a situation is going to improve. The initial saying, taken from one of Aesop’s fables, is “One swallow does not make a spring” (μία χελιδὼν ἔαρ οὐ ποιεῖ), with the swallow sometimes replaced by a cuckoo.…