Mathematics is not a spectator sport. You have to get involved.
处于逆境中,就好比周身都扎着针、敷着药;冥冥中却能磨炼人的意志、培养高尚的品行。处于顺境中,就好比被各种各样的兵器包围;冥冥中掏空了身体,消磨了向上进取的意志。
Efficiency is doing things right; effectiveness is doing the right things.