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 Buddha is your real body, your original mind. This mind has no form or characteristics, no cause or effect, no tendons or bones. It's like space. You can't hold it. It's not the mind of materialists or nihilists. If you don't see your own miraculously aware nature, you'll never find a Buddha, even if you break your body into atoms.
. . . 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.
When mortals are alive, they worry about death. When they're full, they worry about hunger. Theirs is the Great Uncertainty. But sages don't consider the past. And they don't worry about the future. Nor do they cling to the present. And from moment to moment they follow the Way.
All Buddhas preach emptiness. Why? Because they wish to crush the concrete ideas of the students. If a student even clings to an idea of emptiness, he betrays all Buddhas.
But people of the deepest understanding look within, distracted by nothing. Since a clear mind is the Buddha, they attain the understanding of a Buddha without using the mind.