Full Idea
The premises [of a science] ...are pretty certain to lead to a number of new results which could not otherwise have been known.
Gist of Idea
Finding the axioms may be the only route to some new results
Source
Bertrand Russell (Regressive Method for Premises in Mathematics [1907], p.282)
Book Reference
Russell,Bertrand: 'Essays in Analysis', ed/tr. Lackey,Douglas [George Braziller 1973], p.282
A Reaction
I identify this as the 'fruitfulness' that results when the essence of something is discovered.