A buddha is someone who finds freedom in good fortune and bad. Such is his power that karma can't hold him. No matter what kind of karma, a buddha transforms it. Heaven and hell are nothing to him. But the awareness of a mortal is dim compared to that of a buddha, who penetrates everything, inside and out.
If you see your nature, you don't need to read sutras or invoke buddhas. Erudition and knowledge are not only useless but also cloud your awareness. Doctrines are only for pointing to the mind. Once you see your mind, why pay attention to doctrines?
The Way is basically perfect. It doesn't require perfecting. The Way has no form or sound. It's subtle and hard to perceive. It's like when you drink water: you know how hot or cold it is, but you can't tell others.
If you use your mind to study reality, you won't understand either your mind or reality. If you study reality without using your mind, you'll understand both.
Whoever realizes that the six senses aren't real, that the five aggregates are fictions, that no such things can be located anywhere in the body, understands the language of Buddhas.