得鱼忘筌

déyú-wàngquán

[forget the means by which the end is attained; forget the trap as soon as the fish is caught] 筌是用来捕鱼的器具。 得到了鱼, 就忘掉筌。 比喻达到目的以后就忘了赖以成功的东西

筌者所以在鱼, 得鱼而忘筌。 --《庄子·外物》