Abstract This article examines the time duration of individual occasions in the light of the discovery that temporal succession produces frequency ratios. The frequency ratios are used to define energy ratios and the quantum. The manifold and the common particles are constructed graphically using the arrows of time, with the mass-ratios of the particles derivable from the graphs. The formal reduction of physics to time compels us to adopt Whitehead’s conception of the physical universe as occasions of experience engaged in temporal/causal succession. The relative duration of the constituent occasions of the particles are determined by their graphs. In the final section, a refined account of the mind-brain interaction sequence confirms the duration of a human occasion as one tenth of a second.