“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found the object of his search. I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
Having read extensively about both Edison and Tesla, my personal theory is that one of the reasons Edison championed DC power over AC is that he didn't UNDERSTAND AC, especially the concept of muti-phasic AC, which is what makes the AC system really work. He was very much a DC sort of guy, who had essentially no theory behind his inventions beyond what he saw worked. That is why he had the quote about genius being 1% inspiration and 99% perspiration. One other problem he had was that even though Maxwell had published his definitive theory of electromagnetism before Edison even really started his career, Maxwell's prose was incredibly impenetrable -- especially for someone with as little formal education as Edison. Additionally, most of the real further work on the theory of electromagnetism was done in Germany (the scientific and technical hub of the world till the 1930's) and published in German, which Edison of course did not read. Tesla, on the other hand, studied electrical theory in Austria, spoke and read German, and had a mental gift for taking a bit of theory and constructing entirely complete inventions in his head. He considered the actual construction of the devices as little more than an afterthought.