Diogenes Laertius Vitae philosophorum 8.1.15

[15] Down to the time of Philolaus it was not possible to acquire knowledge of any Pythagorean doctrine, and Philolaus alone brought out those three celebrated books which Plato sent a hundred minas to purchase. Not less than six hundred persons went to his evening lectures; and those who were privileged to see him wrote to their friends congratulating themselves on a great piece of good fortune. Moreover, the Metapontines named his house the Temple of Demeter and his porch the Museum, so we learn from Favorinus in his Miscellaneous History. ¹ And the rest of the Pythagoreans used to say that not all his doctrines were for all men to hear, our authority for this being Aristoxenus in the tenth book of his Rules of Pedagogy,