Full Idea
For Mill, explanation was always the fitting of facts into ever more general patterns of regularity.
Gist of Idea
Explanation is fitting of facts into ever more general patterns of regularity
Source
report of John Stuart Mill (System of Logic [1843]) by David-Hillel Ruben - Explaining Explanation Ch 6
Book Reference
Ruben,David-Hillel: 'Explaining Explanation' [Routledge 1990], p.201
A Reaction
This seems to nicely capture the standard empirical approach to explanation. If you say that this fitting in doesn't explain much, the answer (I think) is that this is the best we can do.