Psychotechnical locks (applied psychology)

One method was to call on gods; people have believed in gods in all ages, and have always been uncertain about what shapes gods may appear in. They sought divine protection from someone who could mete out punishment, while those who tried to trick the gods were punished.

Mysteries, secret rites and magic were used to keep people safe. Mysterious figures drawn on the walls or on a piece of wood may have been “keys” or have indicated taboos in given rooms. A short, magical written formula or text, “codes”, could be enough to keep unwanted visitors out. So could writing on the wall on the door: “Here lives the mighty Heracles – no evil may enter.” Other ways to confuse would-be intruders is by using secret doors and passageways with labyrinths.

“Intimidation locks” were also used to frighten thieves away. They might be scary images or stuffed wild animals, such as a lion or tiger.

Interior doors to special rooms and areas could be protected by the impression of a signet ring in clay, wax or lead seals. Artistic, magical knots could also keep evil away, along with wooden cross beams.
It’s possible that people believed that gods revealed their presence through the use of symbols such as birds, butterflies, cocoons or divine symbols such as a double-headed ax or holy knots.