 His answer has earned the label ‘Frege’s trick’. The sought concept would be none other than ‘successor∗xn’, i.e., “x is a natural number preceding or identical to n”. The natural numbers relentlessly generate ever more of their kind, as soon as we try to count them. This is why there are infinitely many of them. The idea that each natural number tallies its predecessors in the series of natural numbers was fully formed in the Grundlagen, at §82, and rigorously executed in Volume I of the Grundgesetze, at §§114–119. 