投筆從戎 [ㄊㄡˊ ㄅㄧˇ ㄘㄨㄥˊ ㄖㄨㄥˊ; tou2 bi3 cong2 rong2] to lay down the pen and take up the sword (idiom) to join the military (esp. of educated person) ◄ ►