Arthur was notice worldwide after Peter Snell's, Murray Halberg's and Barry Magee's performances at the 1960 Olympics. Before that point he spent a good part of 15 years developing his system using himself as the subject. What he learned from these years as much to do with the nervous system as it did with the cardio-respiratory system and muscular systems.
Arthur's earlier (pre 1964) talks and writings referenced the nervous system as much or more than the cardio-respiratory or muscular systems. With quotes like "I have found the marathon training not only increased efficiency of the cardio-respiratory system more quickly but also had a more beneficial effect on the nervous system", "We all know we have to be racing fit to win championships but if we were to race and do fast work continually , the strain would eventually wear down our condition so that we become jaded mentally and physically" and finally "Train don't strain"
One point I watch for as a coach is how well runners follow the "train don't strain" advice. During the Marathon conditioning phase I love to see post that say "I don't feel like I'm training", "My legs just floated along" and "Just drifted along for two hours". They all indicated that the mind is not using valuable willpower that will be needed during the speed phase. Running and recovery have become a habit with no though given to pushing things (like pace and recovery).
The nervous system only has to be gradually stressed over 3-6 weeks and left to recover for 2-4 to achieve a top performance. I see runners push too long with too many long runs or hard speed workouts and they end up as Arthur said "Leaving it on the training track".
So for the coming year make sure that during the Marathon training phase you use your willpower to roll out the door then switch to turning off the willpower and make that run an enjoyable experience that you'll want to visit again the next day.
Have a Happy and successful New Year.