The Mysteries of Initiation: From Isis to the Holy Grail CW 144, a cycle of four lectures by Rudolf Steiner given in Berlin between 3 and 7 February 1913. Translation revised by Charles Davy.
(provisional titles below)
The whole book as a zip file.
1. Lecture 1: The mystery being in its connection with the spiritual life of Mankind. (Berlin, 3 February, 1913)
2. Lecture 2: The strengthening of the soul forces as prerequisite for the ascent into higher worlds. (Berlin, 4 February, 1913)
3. Lecture 3: Further stages of ascent into the spiritual worlds. (Berlin, 5 February, 1913)
4. Lecture 4: Mystery secrets of Egyptian sentient-soul re-appear in King Arthur's Round Table.(Berlin, 7 February, 1913)