Tenets

The tenants are the rules the assassins live by:

1.Still your blade from the flesh of the innocents

2.Always remain subtle

3.NEVER endanger the brotherhood, in other words don't bring the templars back to masyaf.

Altaïr breaks all 3 of the tenants in the beginning of the game and as a result, lost his rank, if you break, say the first tenant, Altaïr will die and the screen will say: desynchronized, reason: killing innocents; first tenant. There is also an achievement you can unlock if you don't break ANY tenants throughout the game.