When the Doors became huge, what nascent rock intelligentsia existed at the time adored them.

The doors of wisdom are never shut.

There are things known and things unknown and in between are the doors.

There are things known and there are things unknown, and in between are the doors of perception

There are things known and there are things unknown, and in between are the doors of perception.

There's a policy now of opening the doors to the outside world.