You will admit all this in a moment, Ctesippus, if you answer my
questions, said Dionysodorus. Tell me, have you got a dog?
Yes, and a brute of a one, too, said Ctesippus.
And has he got puppies?
Yes indeed, and they are just like him.
And so the dog is their father?
Yes, I saw him mounting the bitch myself, he said.
Well then: isn’t the dog yours?
Certainly, he said.
Then since he is a father and is yours, the dog turns out to be your
father, and you are the brother of puppies, aren’t you?

Plato, Euthydemus, 293e et seq.