Knock, knock

Great Knockers, Rome, Italy, September 2005, Pentax Optio 555, Exposure 1/50 sec @ f2.8, ISO 64, with flash © Steven Crisp

Ask and it will be given to you
seek and you will find
knock and the door will be opened to you.
For everyone who asks receives
he who seeks finds
and to him who knocks, the door shall be opened.
-- Jesus

Or consider:

When the Sufi saint Rabi'a heard Salih of Qazwin teaching "Knock and the Door will open for you" she admonished him. "What are you talking about Salih, the Door has never been shut."

The great mystic poet Jalaluddin Rumi wrote, "I knocked and the door opened, but I found I'd been knocking from the inside"