[articulatepang]

Sureness is most certainly a word! It has been used by writers of the stature of Emerson ("the law holds with equal sureness for all right action") and Edith Wharton ("“The moment the reader loses faith in the author’s sureness of foot the chasm of improbability gapes.”)

It used to mean "certainty", as when T. H. Howard writes, "Uncertainty about our religious condition is quite as unsatisfactory as any doubt about our most sacred domestic relationships. Sureness is vital to peace, and the truly sanctified soul will live in the region of certainty."

But in more modern usage the word has a connotation slightly different from what the author of this library intends. Its meaning is closer to "assuredness": confidence matched with ability. For example, "Proust had an incredible sureness of touch in shedding this prophetic ray on his characters." (again from Edith Wharton).

[pimlottc]

Point taken. It's not really a common word in modern usage, and probably not really the word the author wants here.