 For the premise asserts that the graph of the function \(g: \Delta \rightarrow \bR\) defined by \(g(\varepsilon) = a \varepsilon\) has both slope \(a\) and slope \(b\): the uniqueness condition in the principle of microaffineness then gives \(a = b\). The principle of microcancellation supplies the exact sense in which there are “enough” infinitesimals in smooth infinitesimal analysis.