Why is Pip curious about dining with Mr. Jaggers?

Wemmick wants Pip to examine Jaggers' housekeeper.

Well," said Wemmick, "you'll see a wild beast tamed. Not so very uncommon, you'll tell me. I reply on the original wildness of the beast and the amount of taming. It won't lower your opinion of Mr. Jagger's powers. Keep your eyes on it."