Fascinating that within a section or prose about indexing within MiddleMarch (set in 1829 to 1832 and published in 1871-1872), George Eliot compares a character's distinguished appearance to that of John Locke!
Mr. Brooke asks for advice about arranging notes as he has tried pigeon holes but has the common issue of multiple storage and can't remember under which letter he's filed his particular note. Mr. Casaubon indicates that he uses pigeon-holes.
Dorothea Brooke mentions that she knows how to properly index papers so that they might be searched for and found later. She is likely aware of John Locke's indexing method from 1685 (or in English in 1706) and in the same scene compares Mr. Casaubon's appearance to Locke.