源自《圣经》，指豹子身上的斑点是天生的，无法改变。用来形容人的性格、习性或本质一旦形成，就很难再发生改变。

• He promised to stop lying, but a leopard can’t change its spots. ^{他承诺不再撒谎，但江山易改本性难移。}
• I don’t think he will ever be punctual; a leopard can’t change its spots. ^{我不觉得他能变得守时；本性难移。}
• It’s hard to trust him again; a leopard can’t change its spots. ^{很难再信任他了；本性难移。}