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.
. . . the fools of this world prefer to look for sages far away. They don't believe that the wisdom of their own mind is the sage . . . the sutras say, "Mind is the teaching." But people of no understanding don't believe in their own mind or that by understanding this teaching they can become a sage. They prefer to look for distant knowledge and long for things in space, buddha-images, light, incense, and colors. They fall prey to falsehood and lose their minds to insanity.
To have a body is to suffer. Does anyone with a body know peace? Those who understand this detach themselves from all that exists and stop imagining or seeking anything. The sutras say, "To seek is to suffer. To seek nothing is bliss." When you seek nothing, you're on the Path.
The mind's capacity is limitless, and its manifestations are inexhaustible. Seeing forms with your eyes, hearing sounds with your ears, smelling odors with your nose, tasting flavors with your tongue, every movement or state is all your mind.
Still others commit all sorts of evil deeds, claiming karma doesn't exist. They erroneously maintain that since everything is empty, committing evil isn't wrong. Such persons fall into a hell of endless darkness with no hope of release. Those who are wise hold no such conception.
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?
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.