But from a brief reading I must say that there is a very precise, very simple, graphical way of understanding it. It just requires a deceleration-acceleration traffic jam of cars in a straight line; another such jam imagined as superposed at right angles to the first jam; choose a car in each jam and track their combined position through both jams; then rotate that curved summation path so it becomes straight; superpose another linear traffic jam at right angles to it; track a new combination of cars in each jam; get a new curved path; rotate it; etc.

It looks like you will get a great deal made very clear; you will I suspect be able to see Dick's delta arguments made clear/ see quantum spin/ E=mc squared/ Maxwell's equations/ Relativity/ mass as 4th axis momentum/ most or all of Dick's technical math in his paper/ etc. !

-dolphin