Latin Rule
The Latin Rule was a document formed in the twelfth century by French Templar masters Bernard de Clairvaux and Hugues de Payens to outline the perfect behavior of an ideal Templar Knight. It was originally known as "the Specific Behavior of the Templar Order", and drew upon the already-existing rules of the Order.
It originally consisted of 72 clauses, but was revised several times over the course of the next hundred years, eventually covering various subjects from the Order's hierarchy to the clothing worn by members. However, most of the mandates are considered more ceremonial than functional by modern Templars.
History
The Rule was first written with 72 articles by Clairvaux and Payens in 1128 and was made into official doctrine in 1129. Although it was intended for use by the Order's scholars, it was easily adapted for use by active, military knights serving the Order in the Second and Third Crusades. In 1138, the Rule was revised by the second Grand Master of the Templar Order, Robert de Craon, translating it from Latin to several other languages, allowing it to spread more easily throughout the Order's members.
Chief among the rules were those that concerned the secrecy of the Order, the need for conviction to the cause of the Templars, and the need for piety and poverty among the Knights. These core values were already part of the Order, but had not been formally written until Clairvaux and Payens did so.
Some time later, the Rule was revised once more, this time to include over 600 articles that covered varied topics, which, when all followed, would dictate almost every detail of a Knight's life. However, throughout the years, almost all of the newest rules were considered more ceremonial than applicable, as they eventually became more accustomed to the power and wealth that their order bestowed upon them.
From that point on, the rules remained virtually unchanged, and it is unknown if they are still part of the training recieved by Templar initiates.