The door
Examples
The courage of the poet is to keep ajar the door that leads into madness.
Philosophy is like trying to open a safe with a combination lock: each little adjustment of the dials seems to achieve nothing, only when everything is in place does the door open.
By increasing the size of the keyhole, today's playwrights are in danger of doing away with the door.
The smaller the cabin the wider the door.
When in someone else's home leave your defects at the door.
Who stands by the door of his house is not yet gone away.