Full Idea
To say that mathematics is logic is merely to replace one undefined term by another.
Gist of Idea
Saying mathematics is logic is merely replacing one undefined term by another
Source
Haskell B. Curry (Remarks on the definition and nature of mathematics [1954], 'Mathematics')
Book Reference
'Philosophy of Mathematics: readings (2nd)', ed/tr. Benacerraf/Putnam [CUP 1983], p.206