Full Idea
Only what is logically complex can be defined; what is simple can only be pointed to.
Gist of Idea
Only what is logically complex can be defined; what is simple must be pointed to
Source
Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §180), quoted by Harold Hodes - Logicism and Ontological Commits. of Arithmetic p.137
Book Reference
-: 'Journal of Philosophy' [-], p.137
A Reaction
Frege presumably has in mind his treasured abstract objects, such as cardinal numbers. It is hard to see how you could 'point to' anything in the phenomenal world that had atomic simplicity. Hodes calls this a 'desperate Kantian move'.