The exposition of these definitions and the preliminary explanations necessary will, I hope, serve as a general explanation of the function of event-particles in the analysis of nature.
We note that event-particles have 'position' in respect to each other.
In the last lecture I explained that 'position' was quality gained by a spatial element in virtue of the intersecting moments which covered it.
Thus each event-particle has position in this sense.

The simplest mode of expressing the position in nature of an event-particle is by first fixing on any definite time-system.

Call it {alpha}.

There will be one moment of the temporal series of {alpha} which covers the given event-particle.

Thus the position of the event-particle in the temporal series {alpha} is defined by this moment, which we will call M.The position of the particle in the space of M is then fixed in the ordinary way by three levels which intersect in it and in it only.