It jumps from advanced to introductory and then to intermediate. Is my mind now really trained to think in perfectly musical fourths? What would Joey Ramone do? How about Yianni? Can you dance to it?
It seems as though our instructor, famed Television co-guitarist Richard Lloyd was under pressure from the producers to fit everything into a time frame and this makes me want to squirm. After all Richard teaches guitar lessons and it behooves him to pique our interest. Richard also puts a mystical slant on these 'sacred' teachings which in its way gives credit to where credit is due.
The ancient Greeks and specifically Pythagoras of Samos. Pythagoras was a cult figure even when he was alive - sort of Jim Jones but without the Kool-aid. Pythagoras got around and subsequently set up camp in Italy where the Greeks had established some colonies and the taxes were more reasonable.
Anyway back then they were looking for truth and they considered numbers to be truths. I guess Pythagoras was the first guitar geek. I am not even going to try to explain Pythagoras the founder of string theory and a lot more apparently but he had a following and was a mathematician and geomancer.
He had a string, something disgusting no doubt, which he would stretch taught and divide into intervals of a half, a third, a fifth a seventh and so on and listen to the sounds produced.
It turns out the best way to make the string make sense was to have 12 intervals. Seven of those 12 sounded consonant so those seven were chosen to make up the major scale the rest of the notes are called incidentals.
Consonant is another word for sounding good or harmonious which you can hear for yourself. Soon they figured out that you could start an inervallic pattern on any of the notes and play in modes of the parent scale.
The Ionian mode for example is just another name for the major scale which we all playing western music use today. On the guitar you need to familiarize yourself with it in 5 positions to start to get familiar with all the possibilities.
Pythagoras was the first guy perhaps to suss this out for us and wanted to make a religion out of it. Music was cosmic truth then too and even today a lot of road house boogie blues hip hop dance trance etc and so on uses the Mixolydian mode for the bass patterns. How hip is that? That's a minor mode you run into real quick. Its one of the few modes you need to worry about to have fun.
Your present circumstances don't determine where you can go; they merely determine where you start.