During his later scientific career, Hermann von Helmholtz (1821-1894) published several papers on the principle of least action and related variational principles. These papers include historical investigations about these principles and the concept of action (‘Wirkung’) as well as philosophical reflections on their epistemological relevance and their status within philosophy of science. In addition, Helmholtz pursued a generalization of the least action-principle for mechanics, thermodynamics and electrodynamics. The respective papers seem highly interesting with respect to his aim to achieve a unified view of theoretical physics and with respect to the ‘modernisation’ of mechanism in general which took place in the last three decades of the 19th century. In this context, his various “Studien zur Statik monocyklischer Systeme” (1884) and his “Ueber die physikalische Bedeutung des Princips der kleinsten Wirkung” (1886) deserve special attention.

My talk will focus on the historical origin and the philosophical relevance of the principle of least action in Helmholtz’s articles in relation to his principle of energy conservation. His ‘Studien’ from 1884, rarely investigated until now, are reconstructed as an update of earlier attempts to eliminate the concept of force from physics by means of variational principles – an update which influenced his student Heinrich Hertz and culminated ten years later in Hertz’s ‘Principien der Mechanik’ (1894).