yǐn yù zhī zhuān
lit. a brick thrown to prompt others to produce a jade (idiom)
fig. a modest suggestion intended to prompt others to come forward with better ideas
引
yǐn
to draw (e.g. a bow)
玉
yù
jade
之
zhī
(possessive particle, literary equivalent of 的[de5])
砖
zhuān
brick