GA 75
| Date | Title | City |
|---|---|---|
| 17 Jun 1920 | Spiritual Science. Natural Science. Technology | Stockholm |
| 08 Jul 1920 | Philosophical Basis for Anthroposophy | Bern |
| 04 Jun 1921 | Science and Anthroposphy | Weimar |
| 04 Jun 1921 | Science Questions | Weimar |
| 02 Nov 1921 | Anthroposophy and Science | Basel |
| 11 May 1922 | Agnosticism in Science and Anthroposophy | Leipzig |