Manly P Hall is one of the most intriguing figures I have aver come across.  At the age of 27, he published an incredible encyclopedic volume of study entitled An Encyclopedic Outline of Masonic, Hermetic, Qabbalistic and Rosicrucian Symbolical Philosophy: The Secret Teachings of All Ages. He spent his entire life giving over 8000 lectures and sharing a mysteriously bottomless reservoir of deep understandings of ancient symbology and cosmic knowledge of the ages.

There is a vast amount of talks on YouTube where you can hear him speak, here is just one sample that I particularly like he gave near the end of his life;

Part 2  Part 3 Part 4 Part 5 Part 6 Part 7 Part 8 Part 9