Full Idea
For Frege, coming to a full understanding of logical structure is necessary to full understanding of a thought. And understanding logical structure derives from seeing what structures are most fruitful in accounting for the patterns of inference.
Gist of Idea
To understand a thought you must understand its logical structure
Source
report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Tyler Burge - Frege on Knowing the Foundations 4
Book Reference
Burge,Tyler: 'Truth, Thought, Reason (on Frege)' [OUP 2001], p.354
A Reaction
To me, the notion of finding what is 'fruitful' implies finding the essence of the structure.