#4-character idioms
不 = not
言 = speaking
実 = actually
行 = doing
The second and fourth character in this famous 4-character idiom are both 心, which means “heart”. This idiom refers to heart-to-heart communication; speaking without words.
This is a “yo-ji-juku-go” (Japanese 4-character idiom), which describes how to live a peaceful yet productive life: work when it’s sunny, and rest when it rains. Doing everything in its proper season.