As I said and other contributions like the flaps, the efficient use of petrol engines, etc..
And he did all that for fun, he abdicated all inventions rights and all money.
1 (+/- a couple of years) - Jesus born. Pretty big I guess.
~400 BC - The library of Alexandria was destroyed. The biggest setback for science through history.
Well, in I guess, though I don't think we lost as much and not nearly as sudden as in Alexandria. Hard to put a specific year on it too as it went down during a quite long time.
Saw one program where they said the contents of the library werent so much lost as only dispersed. Apparently most invaders saw collections of manuscripts as valuable to be taken not destroyed...