Teachers, like candles burning to ash, devote their whole lives to education.
Tips
history
From Li Shangyin 李商隐's Tang 《无题·相见时难别亦难》: ‘春蚕到死丝方尽,蜡炬成灰泪始干。’ (The spring silkworm does not finish its silk until it dies; the candle's tears do not dry until it is ash.) Originally about an aching love; in the PRC it was reinterpreted as a metaphor for teachers' self-sacrifice and is widely used on Teachers' Day.
usage
蜡炬 = wax candle. The ‘tears’ are the candle drippings. Always quoted with the silkworm line. In the poetry, 丝 (silk) puns on 思 (longing).