The Master Key System, along with âThe Science of Getting Richâ is the source of Rhonda Byrneâs inspiration for the book and film âThe Secret.â Originally published in 1912 as a correspondence course, it teaches that everything around us was first developed as a thought. That means that thought, is the powerful catalyst towards turning any idea into a reality. Using thought as the manifestation of creative energy, The Master Key System will show you how to use the power of these thoughts to realize your dreams.