Help those who help you.
毒蛇和锉刀
The Viper and the File
一条毒蛇偷偷溜进一家铁匠铺，想寻找一些吃的。这时他遇到了锉刀，就求他施舍一点儿吃的东西。锉刀摇摇头对他说：“愚蠢的家伙啊！难道你想以你的牙齿为代价从我这里得到一丁点儿食物？你可知道我是可以咬透各种坚硬的铁的。”
这则寓言针对那些想从比自己强的人的手里得到好处的人。
A Viper entered a blacksmith’s workshop and bit the file，testing it to see if this was something he could eat. The file protested fiercely，“You fool！ Why are you trying to wound me with your teeth，when I am able to gnaw through every sort of iron？”