(as) bright as a button
Intelligent and quick thinking. Ted's as bright as a button, so he'll find a solution to this problem. Of course Ellen is our valedictorian—she's bright as a button.
as bright as a button
intelligently alert and lively. informal There is a play here on bright in its Old English sense of ‘shiny’ (like a polished metal button) and bright in its transferred sense of ‘quick-witted’, found since the mid 18th century.