The Essence of Anthroposophy
GA 80a
| 1. | The Difference Between Calculation and Operation | 19 October 1904 |
| 2. | Ellipse, Hyperbola, Lemniscate, Circle | 26 October 1904 |
| 3. | Trigonometry | 4 November 1904 |
| 4. | Sine, Cosine, Tangent, Cotangent | 9 November 1904 |
| 5. | The Fourth Dimension I | 21 August 1906 |
| 6. | TThe Fourth Dimension II | 23 August 1906 |
| 7. | The Fourth Dimension III | 25August 1906 |
| 8. | The Fourth Dimension IV | 27 August 1906 |
| 9. | Christ And Luzifer | 31 August 1906 |
| 10. | The Molten Sea | 7 August 1905 |
| 11. | The Interconnection Between the Three Worlds and the Natural World | 8 August 1905 |
| 12. | The Descent of Man | 9 August 1905 |
| 13. | Light on the Path I | 10 August 1905 |