Straight wood
The ancients believed that the wild geese follow the sun and the trees follow the sun. It's a metaphor for good talent.
Idiom and allusion [source] "the biography of Yuan ang in the book of Liang Dynasty": "the humble official of the eastern Kingdom, who can learn and do what he wants to do, has no ribbon and no crown because of the special singing of wild geese and straight wood."
Straight wood
answer as quickly as the flowing of water - yìng dá rú liú
there 's no making without breaking - bù può bù lì
see the scene which is dreadful to one 's mind - chù mù jīng xīn