* The unavoidable character of this interference of measurements appears from another standpoint to be due to the discreteness of the quantum of action (Bohr, Atomic Theory and the Description of Nature). So, though Eddington’s arguments show that we may have to give the probability concept a fundamental place in physical theory, it is difficult to admit at this stage that we are compelled to do so. All this is somewhat aside from the general circumstance that every prediction of the future is implicitly a statement of a probability