Full Idea
When you have enumerated all the atomic facts in the world, it is a further fact about the world that those are all the atomic facts there are about the world.
Gist of Idea
Once you have enumerated all the atomic facts, there is a further fact that those are all the facts
Source
Bertrand Russell (The Philosophy of Logical Atomism [1918], §V)
Book Reference
Russell,Bertrand: 'Russell's Logical Atomism', ed/tr. Pears,David [Fontana 1972], p.93
A Reaction
There is obviously a potential regress of facts about facts here. This looks like one of the reasons why the original logical atomism had a short shelf-life. Personally I see this as an argument in favour of rationalism, in the way Bonjour argues for it.