6 ideas
| 9565 | Zermelo made 'set' and 'member' undefined axioms [Zermelo, by Chihara] |
| 3339 | For Zermelo's set theory the empty set is zero and the successor of each number is its unit set [Zermelo, by Blackburn] |
| 579 | Cratylus said you couldn't even step into the same river once [Cratylus, by Aristotle] |
| 578 | Cratylus decided speech was hopeless, and his only expression was the movement of a finger [Cratylus, by Aristotle] |
| 22363 | You have only begun to do real science when you can express it in numbers [Kelvin] |
| 20644 | Energy has progressed from a mere formula, to a principle pervading all nature [Kelvin] |