Aristotle became not only the most important mouthpiece of Greek dramatic criticism but also one of the most important influences in all the history of literature. He analyzed the plays of the fifth century just as those of his own time, arranged the kinds of drama, and set down principles for the development of tragedy.
Alexander Kerensky might have remained as prime minister of the provisional government a lot longer. He may have succeeded in keeping Russia in WWI. The war may have ended sooner than 11/1918 with the U.S. entering in 1917.