How about most important DATE in history? My vote goes to June 6, 1944. If it wasn't for that date, we'd all be speaking German (or Japanese). Another crucial date in Western Civilization is October 14, 1066. How could nobody mention the Norman Invasion before? Britain (and, by extension, the US) could not have existed in its later form without the Norman influence.
I'd have to nominate two things I didn't see that in my opinion has separated men from the animals:
1) harvesting of fire, I know the dates varied by culture but it allowed us to stay warm, eat sterilized food, and fashion tools.
2) the developement of compound tools, namely in both the form to reduce work (plant/harvest food easier) and give us an edge over animals stronger, faster, and hardier than what we once were.
Though thoughts, philosophy, and ideas are great, they usually came way after this.