Source: Quote Investigator, date indeterminate
Quote Investigator: The earliest strong match known to QI appeared in a 1901 autobiography by Charles Stewart. As a child in London, Stewart listened to the conversation of dinner guests such as history scholar Henry Thomas Buckle who would sometimes discourse engagingly for twenty minutes on a topic. Boldface has been added to excerpts: 1
His thoughts and conversation were always on a high level, and I recollect a saying of his, which not only greatly impressed me at the time, but which I have ever since cherished as a test of the mental calibre of friends and acquaintances.
Buckle said, in his dogmatic way: “Men and women range themselves into three classes or orders of intelligence; you can tell the lowest class by their habit of always talking about persons; the next by the fact that their habit is always to converse about things; the highest by their preference for the discussion of ideas.”