Full Idea
Frege is known for the idea that we do not have objects without concepts. Without concepts, there is nothing - no thing - to count.
Gist of Idea
Without concepts we would not have any objects
Source
report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Stewart Shapiro - Philosophy of Mathematics 8.4
Book Reference
Shapiro,Stewart: 'Philosophy of Mathematics:structure and ontology' [OUP 1997], p.257
A Reaction
A very helpful clarification. Thinking about the probable mental life of higher and lower animals, the proposal seems extremely plausible. Dogs have some concepts, slugs have none, so slugs do not exist in a world of objects. I like it.