Buried treasure

I stumbled across this buried treasure
Learned the secrets from a book
Extraordinary insight to the lowly and great
How others learned the secret, I do not know
Life must be lived in the will, not emotions
At birth the gift of freedom of will
The central citadel of man’s being
He stands knocking on the door of the human heart
But the latch of the door is on the inside
This is the entering-in