Where did the superstition not to walk under a ladder come from?

The superstition against walking under a ladder is thought to have originated from ancient symbolism; a triangle formed by a ladder against a wall is often associated with the Holy Trinity in Christianity. Walking through this triangle was believed to be disrespectful or could invite bad luck. Additionally, from a practical standpoint, walking under a ladder posed a safety risk, which may have contributed to the superstition's persistence. Over time, these beliefs merged into a widely recognized superstition.