By merit of being born in the eighteen-hundreds, I'm sure.

[In all honesty, Ciel has very little confidence he'll make it that long. He does the small situation of his butler and their contract. Never mind that he's purposely trying to get his families murderers to come after him.]

Perhaps he gained more confidence with the publication of his books? Although he did comment that his books and the subjects were outside of his area of expertise. He really must have done his research.