abandon the pen for the sword; cast aside one's books and take up military life;desert letters to become a soldier;lay down the pen for the sword;quit civilian life and join the military;the book is laid aside for the gun
弃旧迎新: replace the old with the new; change the new for the old; denounce the old and hail the new; prefer new to old acquaintances; throw sb. over for a new acquaintance; turn back on sb. (lover