Idioms 4: And it came to pass

Καὶ ἐγένετο ἐν ἐκείναις ταῖς ἡμέραις

And it came to pass in those days. Mark 1:9a

This is more of a Jewish transitional clause than an idiom.  It was a way to introduce a new subject or event.  In the greek, the passage literally says, “and it became in those days.”  I think “and it came to pass” is a wonderful english translation of this transitional clause.