2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/106515From its very beginning, Quantum Theory developed contrary to the intentions of its creators. For Max Planck it marks the failure of a long-term research program, in which he tried to understand the 2nd law of thermodynamics deterministically in terms of mechanics and electrodynamics. For Albert Einstein it meant a refutation of his scientific credo. I describe parts of the early stages of this most remarkable development, up to Einstein's light-quantum hypotheis and its unfavourable reception by most other physicists.29 pages, 4 figures. Text in german. Contribution to the 2005-annus-mirabilis celebration at the Alte Kantonsschule AarauHistory and Philosophy of PhysicsQuantum Physicstext