Nichiren Daishonin (February 16, 1222 – October 13, 1282) with his life and work, established the simple truth that access to the means of attaining enlightenment was public domain and needed no priests or organization or commission agents.
Through his early years, he studied the Buddhist commentaries available to him, and in the face of hostility to his disagreements with the prevailing schools of buddhism in the 13th century, he established what we now know as Nichiren buddhism, spearheaded globally today by the SGI with about 20 million practitioners.
While commenting at length on the correct teachings of Shakyamuni Buddha as contained in the Lotus Sutra, he focused on Buddhahood not only being accessible but contained by default within all living beings. My having been able to encounter his writing in this lifetime is the greatest benefit I can ever imagine receiving. I trust you will find out more about him, a lot of my references to him are scattered in my writing.