4 ms·

A category maybe? Wait a sec... everything already is a category.

• cscurmudgeon 9y ago
  And a set.
  • dboreham 9y ago
    I thought it was known that not everything is a set?
    • johncolanduoni 9y ago
      There’s more than one way to define what a set is, and many of these definitions always allow you to postulate there exist further collections that cannot meet that definition of a set ad infinitum. Most importantly ZFC (which is at least in theory the formal basis for the vast majority of mathematics) has this property, and so do many extensions like NBG and TG.
    • chestervonwinch 9y ago
      of course - it's the empty set :)
    • deleted 9y ago
      [deleted]