There will be two other parts coming soon (I hope). But I just found by chance an old manuscript on the Cornell server which has incidentally the same structure as my insights will have. It's a pdf of 172 pages and for free: https://pi.math.cornell.edu/~hatcher/Other/Samelson-LieAlg.pdfWhat a timing! I was going to study lie algebras, when you posted this insight. That will be truly helpful.