The connection between the Schrodinger equation and Einstein diffusion theory on basis of Brownianmotion of independent particles is well known. However, in contrast to diffusion theory, quantummechanics theory has suffered controversial interpretations due to the counterintuitive concept ofwavefunction. Here, while we confirm there is no difference in the mathematical form of these twoequations, we derive the complex version of displacement. Using diffusion theory of particles in amedium, as simple as it is, we describe that quantum mechanics is just an elegant and subtle equationto describe the probability of all the trajectories that a particle can take to propagate in time by apredictive wavefunction. Therefore, information on the position of particles through time in quantumtheory is embedded in the wavefunction which predicts the evolution of an ensemble of individualBrownian particles.