Full Idea
I protest against the use of an infinite quantity as an actual entity; this is never allowed in mathematics. The infinite is only a manner of speaking, in which one properly speaks of limits ...which are permitted to increase without bound.
Gist of Idea
Actual infinities are not allowed in mathematics - only limits which may increase without bound
Source
Carl Friedrich Gauss (Letter to Shumacher [1831]), quoted by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.7
Book Reference
Clegg,Brian: 'Infinity' [Robinson 2003], p.78