Kasparov writes recently (2013) for http://time100.time.com/ :
'Chess history is best viewed through the game's evolution: the Romantic Era of the 19th century, the Hypermodernism of the early 20th, the post--World War II dominance of the Soviet School. The elite chess players of today are of no school. They hail from all over the world, as illustrated by current world champion Viswanathan Anand of India and young Norwegian Magnus Carlsen, who is due to challenge Anand for the championship this year'
Videos exploring how Style has changed across the hundreds of years the game has evolved