Haydn's Symphonies

I got the whole set of Haydn's symphonies (conducted by Dorati) from Shanghai from my last trip and started to listen to it backwards from the 33rd disc. It was quite an experience - how Haydn managed to compose all these symphonies? He was such a genius! His tunes were capturing and many of the melodies we know today are actually from Haydn. Imagine after a few hundred years, people still recognize a tune written by you? I would be excited to death if I even have one tune recognized by anybody after 10 years of my death!