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.
To enter by reason means to realize the essence through instruction and to believe that all living things share the same true nature, which isn't apparent because it's shrouded by sensation and delusion.
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.
But this mind isn't somewhere outside the material body of the four elements. Without this mind we can't move. The body has no awareness. Like a plant or a stone, the body has no nature. So how does it move? It's the mind that moves.
Externally keep yourself away from all relationships, and internally have no pantings in your heart; when your mind is like unto a straight-standing wall, you may enter into the Path.