He is the so-called father of the modern school of chess; before him, the King was considered a weak piece and players set out to attack the King directly. Steinitz claimed that the King was well able to take care of itself, and ought not to be attacked until one had some other positional advantage. He understood more about the use of squares than Morphy and contributed a great deal more to chess theory.
Bobby FischerI don't recommend trying to cram a lot of long opening-move variations into your head. The main idea behind any opening is to get a strong pawn center and give your pieces a lot of scope so that you cramp your opponent's position and can attack weaknesses in his game.
Bobby Fischer