We are all Buddhas, but not all of us follow the Way.
In order to enter the Buddha Way, one has to make formless repentance, of taking refuge in the Triple Treasure, and vowing to practice the Three Collective Pure Precepts and the Ten Prohibitory Precepts.*
So we write them down in order for you to take good care of them and make them part of your lives.
The Triple Treasure is: I take refuge in the Buddha. I take refuge in the Dharma.
I take refuge in the Sangha.