Never say never, because limits are just illusions.
他让自己被一种信念所左右,即人类并非在母亲生下他们的那一天就一劳永逸地诞生了,而是生活迫使他们一次又一次地重生自己。
If you're not stubborn, you'll give up on experiments too soon. And if you're not flexible, you'll pound your head against the wall and you won't see a different solution to a problem you're trying to solve.