Simplify the following text for a Grade 6 native English-speaking person.
Original: On September 29 , 1947 , he revealed the PL 21 Precepts , the basic teachings of PL .
Simplified: PL does not have a holy book , it has 21 PL Precepts which were announced by Tokuchika Miki on September 29 , 1947 . These became the basic teachings of the Church .