cerberus isn't guarding anyone from getting into hell, but from lost souls from getting out.

Kerberos is of course the original Greek version. It was pronounced with a [k]. The Latin spelling is Cerberus. (Classical Latin famously only uses the letter "K" in one word, Kalendae.) In classical Latin, the pronunciation is still with a [k]. In bastardized medieval Latin, the word would be pronounced with a [ts]. In English, it's naturally just [s].

Jill is quite correct about the purpose of Cerberus. He wags his tail as you go in. Good luck getting out.

Heracles finally captured the dog, overcoming him with brute force. Orpheus and Hermes were both smarter, using two different hacks to get past the dog: music and a drug (Lethe water).

– Stas

Here is how Hesiod puts this:

"a dreaded hound, on watch, who has no pity, but a vile stratagem: as people go in he fawns on all, with actions of his tail and both ears, but he will not let them go back out, but lies in wait for them and eats them up, when he catches any going back through the gates."
Hesiod, Theogony 769 ff

Yes – all the above are correct. Ryan explained it sort of backwards. While Cerberus guarded hell, his job was to keep people in! Now – map that to the private equity business.

Cerberus' main job was to keep the spirits of Hades from getting out. He also kept living people from entering, since once you got in, you never got out. Of course, there are always a few exceptions.

So you're trapped in Hell and try to escape. You end up getting eaten by a three headed dog. Big deal, try again the next day… eventually you'll get through.
Kind of a Groundhog Day aspect to the whole thing.

I think everyone may need a dog ..HAHA
dog is friendly …..!