 In fact Einstein himself had tried this very route in May of 1927 where he proposed a way of “localizing the particle” by associating spatial trajectories and velocities with particle solutions to the Schrödinger equation. (See Belousek 1996 and Holland 2005; also Ryckman 2017.) Einstein abandoned the project and withdrew the draft from publication, however, after finding that certain intuitive independence conditions were in conflict with the product wave function used by quantum mechanics to treat the composition of independent systems. The problem here anticipates the more general issues raised by EPR over separability and composite systems. This proposal was Einstein’s one and only flirtation with the introduction of hidden variables into the quantum theory. In the following years he never embraced any proposal of that sort, although he hoped for progress in physics to yield a more complete theory, and one where the observer did not play a fundamental role. “We believe however that such a theory [“a complete description of the physical reality”] is possible” (p. 780). Commentators have often mistaken that remark as indicating Einstein’s predilection for hidden variables. To the contrary, after 1927 Einstein regarded the hidden variables project — the project of developing a more complete theory by starting with the existing quantum theory and adding things, like trajectories or real states — an improbable route to that goal. (See, for example, Einstein 1953a.) To improve on the quantum theory, he thought, would require starting afresh with quite different fundamental concepts. At Solvay he acknowledges Louis de Broglie’s pilot wave investigations as a possible direction to pursue for a more complete account of individual processes. But then he quickly turns to an alternative way of thinking, one that he continued to recommend as a better framework for progress, which is not to regard the quantum theory as describing individuals and their processes at all and, instead, to regard the theory as describing only ensembles of individuals. Einstein goes on to suggest difficulties for any scheme, like de Broglie’s and like quantum theory itself, that requires representations in multi-dimensional configuration space. These are difficulties that might move one further toward regarding quantum theory as not aspiring to a description of individual systems but as more amenable to an ensemble (or collective) point of view, and hence not a good starting point for building a better, more complete theory. His subsequent elaborations of EPR-like arguments are perhaps best regarded as no-go arguments, showing that the existing quantum theory does not lend itself to a sensible realist interpretation via hidden variables. If real states, taken as hidden variables, are added into the existing theory, which is then tailored to explain individual events, the result is either an incomplete theory or else a theory that does not respect locality. Hence, new concepts are needed. With respect to EPR, perhaps the most important feature of Einstein’s reflections at Solvay 1927 is his insight that a clash between completeness and locality already arises in considering a single variable (there, position) and does not require an incompatible pair, as in EPR.