Sheldon Cooper is nothing if not thorough, and he totally takes after the actor who portrays him! Intrigued?

It should come as no surprise that Jim Parsons bears a resemblance to the genius character he played on the series that made his career, but you have no idea how much of a resemblance we are talking about.

Jim Parsons popped by The Tonight Show Starring Jimmy Fallon to talk about his work and upcoming projects.

Despite being over, the hit sitcom is now reliving its glory – all thanks to The Big Bang Theory 's oral history book, written by Jessica Radloff.

If you ever doubted whether Jim was the right fit for Sheldon Cooper, Parsons revealed the most Sheldon-y fact about his participation in the book.

His interview was literally the longest one: it lasted 20 hours (not in one go, of course, but still pretty mind-blowing)!

The actor was determined to give the author his full perspective on his on-set experiences, so he didn't think that "an hour or two" would cut it. More details, more details, please!

By the way, Jim's meticulous approach to things is what got him the part of Sheldon in the first place.

His audition was so on point that Chuck Lorre couldn't believe that he could do it again! His exact words were, "It was so startling, we were clearly in the presence of brilliance."

Anyway, Parsons remembered the interview experience as "interesting" because in a way it helped him "decompress those 12 years" on the show.

At first, Jim would have his own version of what happened back then, and Jessica would mention another cast member's memory of some event, and Parsons would suddenly go, "That's right. That happened!"

Isn't it fascinating how other people's points of view jog our own memory of this or that?

The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series came out last year and became an instant hit, uncovering all sorts of juicy secrets and exposing the new generation to the show.

Source: The Tonight Show Starring Jimmy Fallon