Doc turns to Marty.

Doc: 1885! Amazing. I actually end up as a blacksmith in the Old West.

Marty: Pretty heavy, huh?

Doc turns back to the letter.

Doc: (reading) "I have buried the DeLorean in the Del Gato mine adjacent to the old Boot Hill Cemetery as shown on the enclosed map. Hopefully it will remain undisturbed and preserved until you uncover it in 1955. Inside, you will find repair instructions. My 1955 counterpart" - that's me - "should have no problem repairing it so you can drive it back to the future. Once you have returned to 1985, destroy the time machine." Destroy it?

During the following Marty is examining the toy car Doc used in the first movie in the demonstration of how he planned to send Marty back to 1985.

Marty: Yeah, well, it's a long story, Doc.

Doc: (reading) "Do not - I repeat - do not attempt to come back here to get me. I am perfectly happy living in the fresh air and wide open spaces, and I fear that unnecessary time travel only risks further disruption of the space-time continuum. And please take care of - Einstein for me." Einstein?

Marty: He's your dog, Doc - Einstein - it's what you call your dog in 1985.

Marty walks over to a chess set, which Copernicus (Doc's 1955 dog) is sitting in front of, and moves a piece. Doc smirks at the mention of Einstein and continues reading.

Doc: (reading) "I know you will give him a good home. Remember to walk him twice a day and that he only likes canned dog food. These are my wishes. Please respect them and follow them. And so, Marty, I now say farewell and wish you Godspeed. You've been a good, kind, and loyal friend to me and you made a real difference in my life. I will always treasure our relationship, and will think on you with fond memories, warm feelings and a special place in my heart. Your friend in time, 'Doc' Emmett L. Brown." This says September 1st, 1885. I never knew I could write anything so touching.