Full Idea
Wittgenstein implies that which concepts a thinker is capable of possessing depends on the ways in which he is capable of finding a natural way to go on.
Gist of Idea
Possessing a concept is knowing how to go on
Source
report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Christopher Peacocke - A Study of Concepts 1.2
Book Reference
Peacocke,Christopher: 'A Study of Concepts' [MIT 1999], p.14
A Reaction
This doesn't seem to amount to much. Presumably someone who failed to grasp a concept would demonstrate the fact by going on in a silly way, and whether or not it was silly might not be obvious. A genius may go on in a quirky way.