  From 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.
