行雲流水

1. • lit. moving clouds and flowing water (idiom)
2. • fig. very natural and flowing style of calligraphy, writing, etc
3. • natural and unforced

Character by character

• 行(xíng)go
• 雲(yún)surname Yun
• 流(liú)flow
• 水(shuǐ)surname Shui