Full Idea
There is a saying that, when we have grasped a concept, we still do not know what to think with it. But there is nothing to be thought with a concept save the concept itself.
Gist of Idea
We don't think with concepts - we think the concepts
Source
Georg W.F.Hegel (Logic (Encyclopedia I) [1817], §03 Rem)
Book Reference
Hegel,Georg W.F.: 'The Hegel Reader', ed/tr. Houlgate,Stephen [Blackwell 1998], p.135
A Reaction
Analytic philosophers should read Hegel on concepts, because he approaches the matter so very differently, and seems to be the root of the continental approach to such things. He seems to me to talk more sense than Frege on the subject.