This volume contains a collection of most notable original papers published in the journal 'Annalen der Physik' written by one of its renowned editors, Max Planck. These papers - reedited on the occasion of the 150th anniversary of his birth - deal with topics which later on took a prominent place in the scientific work of this outstanding physicist: the theory of the emission spectrum of black bodies and the central role of the Second Law of Thermodynamics.

Understanding himself as an all-rounder Max Planck was especially devoted to the German Physical Society and actively involved in the scientific life of his century. His writings depict not only his achievements as a scientist but also shed a light on an era of important discoveries. The facsimiles in this collection are introduced by and complemented with topical articles by well-known physicists and science historians.