 De Broglie’s idea was to modify classical Hamiltonian mechanics in such a way as to make it analogous to classical wave optics, by substituting for Hamilton and Jacobi’s action function the phase \(S\) of a physical wave. Such a ‘wave mechanics’ of course yields non-classical motions, but in order to understand how de Broglie’s dynamics relates to typical quantum phenomena, we must include Bohm’s (1952, Part II) analysis of the appearance of collapse. In the case of measurements, Bohm argued that the wave function evolves into a superposition of components that are and remain separated in the total configuration space of measured system and apparatus, so that the total configuration is ‘trapped’ inside a single component of the wave function, which will guide its further evolution, as if the wave had collapsed (‘effective’ wave function). This analysis allows one to recover the apparent collapse upon measurement (and the quantum probabilities are further recovered via statistical considerations). 