A battering ram can knock down a city wall, but it cannot stop a hole. Different things have different uses.
ZhuangziAn archer competing for a clay vessel shoots effortlessly, his or her skill and concentration unimpeded. If the prize is changed to a brass ornament, the hands begin to shake. If it is changed to gold, he or she squints as if going blind. The abilities do not deteriorate, but belief in them does, as he or she allows the supposed value of an external reward to cloud the vision.
Zhuangzi