Found:
(Between pages 108 and 109 of Papillon in the used book sale perpetually taking place in the entry of the local library)

A 4"x6" envelope with the following features:
- Postmark: "U.S. POSTAL SERVICE, MA 021; 1 PM 6 JAN 1976"
- Stamp: Two blue-and-white 10-cent stamps bearing an image of the Jefferson Memorial, with "We hold these Truths..." on top, just above Jefferson's signature.
- Addressed: In black ink, a woman's name (probably common but certainly unfamiliar), a quite local address currently the site of a real estate establishment.
- Miscellany: "AIR MAIL" is written and twice-underlined in black ink, the word "MAIL" obscuring the year on the postmark; dominating the adhesive flap is a picture of an orange striped kitten looking amiably down and to the right at a small red bird, separated from the kitten by the right diagonal edge of the flap, which is not straight but a series of small arcs; the bird is looking back with an indeterminate expression, and the kitten's tail goes over the top and onto the front of the envelope, just touching the left side of the postmark.

The envelope and kitten are torn, the latter approximately through the midsection, head and ear. The envelope contains a letter, written in cursive in black ink, which reads as follows (names omitted):

[Front]

1/6/76

[Affectionate nickname corresponding to first name of the addressee],
This letter will sound long and complicated, maybe even
cruel in some parts. I hope you can understand it.
I felt that I found the real you on two different
nights. The first time was the night we met at the club.
You seemed so happy and caring. We talked easily and
got along fine. The second time was my first nite in Erie.
On those 2 nights you were exactly the same, a person who
I could share things with and maybe even love with.
All the rest of the time you just seemed to be "going
thru the motions," being polite or talk like you were forced
to. It was like that when we said goodbye the first time
and when I was at your house. You were just plain cold.
The Erie trip had so many events it was unreal.
Thursday nite was fine. Instead of being careful you got a
sunburn and then you were real bitchy on Friday. The
only good thing about our dinner was the food. I ended up
dropping you off at 8:30. Saturday we spent most of the
day waiting for [man's name]. Real fun. Saturday nite I just kept
drinking because I finally got pissed off at you. I
wasn't angry because we didn't sleep together, although
at that time it was the only thing that would have evened
things up. Sunday you said goodbye, but it felt to me that
you wouldn't have cared if I had gotten killed driving home.
[Back]
I know it's cruel but I feel that even now. You just don't
care about me and I care about you. That's why I
write and go to the club - to see you. The only times
you were nice was when you were drinking. If it
takes alcohol for you to be affectionate then we should
both give up. I would even try to come down to Rider
on weekends if we could have a good relationship. And
don't say it couldn't work because I've got friends
who've made it work.
There's only one question I'd like you to answer.
Which person is the real [nickname and last name] - the kind, affect-
ionate person that shows when she's drunk or the cold
and strange one when she's not??

I drove thru N.J. on Saturday on my way to Kentucky.
I was so close, and yet I didn't even stop to see you.
I guess you make me feel unwanted, yet I really want
you. If there's another guy, tell me. The sad thing is
that I might even be able to love that person from
the Playboy Club, yet now I don't know if it's worth
a try. It's up to you now; want to try?
Take care and write me about this, ok.

your friend,
[man's first name]

The last line of the letter is the last line of the paper, spaces were only where I indicated them. The book in which I found it dates back to 1971; perhaps the letter remained there for decades? Otherwise I'm forced to conclude that it held some real significance for the addressee, and perhaps I should make some effort to find her so I can return it. This may be difficult, given the facts: her last name is likely different now, and the address is no longer hers.