4 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] |
| 23221 | The brain, and all the mental events within it, consists entirely of sensitive and rational matter [Cavendish] |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |