The document discusses the meaning and importance of principles of teaching. It defines principles of teaching as the psychological laws of learning, educational concepts, and rules that guide educational procedures. Principles are derived from expert opinions, comparative studies of teachers, and experimental teaching studies. They serve as a basis for intelligent practice and guide instruction to students' capabilities. The document then discusses starting, guiding, and ending principles of teaching and learning as well as techniques, functions, and types of principles. It emphasizes that principles should be based on facts and guide teaching while considering students' nature.