 where the second epsilon replaces \(x\) in \(\phi (x)\), to denote the extension of the concept \(\phi\).  Where ‘\(n\)’ is the name of an object, Frege could define ‘object \(n\) is an element of the extension of the concept \(\phi\)’ in the following simple terms: ‘the concept \(\phi\) maps \(n\) to The True’, i.e., \(\phi(n)\). For example, the number \(3\) is an element of the extension of the concept odd number greater than \(2\) if and only if this concept maps \(3\) to The True.