Just Knock.
Knock and it will be opened.
That sounds just like a quote from the Bible
Matthew 7:7
New International Version (NIV)
Ask, Seek, Knock
“Ask and it will be given to you; seek and you will find; knock and the door will be opened to you.
But now this also fits to a new way of unlocking your Apple MAC, using a “Knock”-App which works with Bluetooth4.0
