Bartleby???

Lets tle (tell) something about Bar-tle-by; pretty interesting name and also a very interesting character. for me although the reading part was kind of boring, overall the story was exciting. this is b'coz i wanted to know what was the problem with such a good copy machine. Bartleby, a scrivener and a very good employee in a law firm, all of a sudden goes silent and doesn't fulfill what is expected of him. his "i would prefer not to" attitude surprises his boss and colleagues; he basically denies his proofreading and copying tasks. after losing his job, Bartleby lands in prison and encounters death.
what was the cause of Bartleby's self-isolation?
now the answer to this is open. you can say either it was a natural death or suicide or murder or depressed or whatever you want. but Bertleby is dead and his death is a mystery.