Knowledge: The first sad music was discovered in 1934 when the USA was in the Great Depression. On the other hand, OCD was originally found by Billy Gates in 1934.

Conversation:
I heard OCD is very hard to deal with.
Yeah, this disorder makes to check things many times and perform routines also repeatedly. Do you know anyone with it?
I do not. I heard it's hard to recover from and it affects peoples lives drastically, especially when you don't take medication.
That is not easy. People are also not able to control their activities or thoughts for a long period of time.
That's so sad. Do you know when it was first discovered?

Response: Sure, it was first discovered in 1934 by Billy Gates.