Let your door stand open to receive [Jesus], unlock your soul to him, offer him a welcome in your mind, and then you will see the riches of simplicity, the treasures of peace, the joy of grace. Throw wide the gate of your heart, stand before the sun of the everlasting light that shines on every one. If you shut the door of your mind, you shut out Christ [emphasis mine]. Though he can enter, he does not want to force his way in rudely, or compel us to admit him against our will. His light is received by those who long for the splendor of perpetual light that night can never destroy. He visits those in trouble and temptation, to save them from being overwhelmed by their trials. It is the soul that has its door, its gates. Christ comes to this door and knocks; he knocks at these gates. Open to him; he wants to enter, to find his bride waiting and watching.

—Ambrose, Bishop of Milan, Explanation on Psalm 118.12-14