4 ideas
10121 | Contradiction is not a sign of falsity, nor lack of contradiction a sign of truth [Pascal] |
18946 | Unreflectively, we all assume there are nonexistents, and we can refer to them [Reimer] |
13165 | Geometrical proofs do not show causes, as when we prove a triangle contains two right angles [Proclus] |
9569 | The origin of geometry started in sensation, then moved to calculation, and then to reason [Proclus] |