Heiliger's diverse output stretches from his early, organically abstracted figures to his late nonobjective, geometric abstractions. His early work (1945–1962), focuses on the human figure, which is treated in an organic style influenced by Aristide Maillol and Henry Moore. Also from this period is a series of portrait busts of prominent contemporary Germans. The artist departed from the human figure in his second period (1962–1970), instead developing imagery of the "flight of birds and vegetable forms" influenced by the nonrepresentational Informel style. The seven-meter-high The Flame (Flamme, 1962–63), commissioned by the city of Berlin for Ernst-Reuter-Platz, is considered the key work in the transition between the early and middle periods. The Five Continents (Die fünf Erdteile, 1961), by contrast, still alludes to the human figure in the torso-like shapes that make up the composition.