be rooted in：植根于；根源在于；来源于。直译即可，不需要拐弯。
I have always been an optimist and I supposed that is rooted in my belief that the power of creativity and intelligence can make the world a better place.
【翻译】我一直是一个乐观主义者，我认为这源自于我的信念，即创造力和智慧可以使世界变得更美好。