Tau symbol

La Tau was already a well-known symbol at the time of St. Francis of Assisi, so its use was no discovery on his behalf. In the time of St Francis, Pope Innocent III, aware of the sad state of the world in which they lived, looked back to the Old Testament prophet Ezekiel for inspiration  “Go all through Jerusalem, and mark a Tau on the foreheads of all who deplore and disapprove of all the evil practices in the city … Do not touch anyone with the sign of the Tau.”

Franciscans are called to always wear a Tau, which is imposed on them since they are aspirants.