The apostle [Paul] teaches us to pray anywhere, while the Savior says Go into your room – but you must understand that this “room” is not the room with four walls that confines your body when you are in it, but the secret space within you in which your thoughts are enclosed and where your sensations arrive.That is your prayer-room, always with you wherever you are, always secret wherever you are, with your only witness being God.
–Saint Ambrose of Milan (339-397)