Throughout his working life, Mueller kept up an enormous correspondence. Large numbers of letters by or to him have been located, scattered throughout the world, and edited for publication. These constitute a major new research tool for both Australian historians and historians of science. They are also of fundamental importance to Australian taxonomic botany, for Mueller introduced vast numbers of Australian plants to western science.

This is the first of three volumes of Mueller's selected correspondence and covers youthful family correspondence, his early botanical activity, his migration to Australia, the building of his scientific career and reputation, his major exploring expeditions, and his first years as director of the Melbourne Botanic Garden. There is a substantial historical introduction and an extensive editorial apparatus that will serve all three volumes.