Full Idea
It is applicability alone which elevates arithmetic from a game to the rank of a science.
Gist of Idea
Only applicability raises arithmetic from a game to a science
Source
Gottlob Frege (Grundgesetze der Arithmetik 2 (Basic Laws) [1903], §91), quoted by Stewart Shapiro - Thinking About Mathematics 6.1.2
Book Reference
Shapiro,Stewart: 'Thinking About Mathematics' [OUP 2000], p.147
A Reaction
This is the basic objection to Formalism. It invites the question of why it is applicable, which platonists like Frege don't seem to answer (though Plato himself has reality modelled on the Forms). This is why I like structuralism.