the art of meaning more than you said, while saying less than you meant
means The practice of using objects, images, or actions to represent ideas beyond their literal selves, especially as an artistic and literary movement that favored suggestion over plain statement.
from From Greek 'symbolon,' a 'token' or 'sign' — literally something 'thrown together' (syn- 'together' + ballein 'to throw'). The original symbolon was a physical thing: a coin or tile snapped in two, each party keeping a half, so that fitting the pieces later proved a bond. The word for that broken token grew into the word for anything that stands in for a larger whole. 'Symbolism' as the name of an art movement is a 19th-century coinage, when poets and painters embraced the half-said and the suggested.