| 1 | Galileo and Descartes replaced that with the idea of inertia. | |
| 2 | This is the kind of perplexing thought Descartes forces us to confront. | |
| 3 | What am I? For Descartes, I am a thinking, doubting agency; and obviously, therefore, I am a mind. | |
| 4 | Well, I'm not going to follow the details of this argument, but the basic idea goes back to Descartes. | |
| 5 | Descartes, the founder of methodological doubt, gave himself the urgent task of proving the existence of God. |