to lay down the pen and take up the sword
to lay down one's weapons 缴械; 缴械 to lay down the pen and take up the sword (idiom) 投笔从戎; 投笔从戎 to lay eggs 产卵; 产卵 ..
投笔从戎是一个成语,读音是tóu bǐ cóng róng,意思是扔掉笔去参军。指文人从军。出自《后汉书·班超传》。