On 4 December 1926 Albert Einstein wrote to Max Born about the new quantum mechanics. He began with respect: Die Quantenmechanik ist sehr achtunggebietend. (Quantum mechanics commands great respect.) Aber eine innere Stimme sagt mir, daß das noch nicht der wahre Jakob ist. (But an inner voice tells me that this is not yet the real thing.) The theory delivered a lot, he wrote, but it hardly brought us closer to the secret of the Old One. Jedenfalls bin ich überzeugt, daß der nicht würfelt. (In any case I am convinced that He does not play dice.) Until his death in 1955 Einstein tried in vain to find a deterministic theory behind it. Experiments later disproved his conclusions. But the observations behind his objections proved correct and fundamental. German Wikipedia says he was the first to put his finger in an open wound.