The meaning of friendship

What is a friend? And who are our true friends?
Is it the people we see most days and spend most days with? (i.e collegues?)
Or is it people who we have a lot in common with and can have long interesting discussions (without falling out) with?
Or is it the ones who we can sit in total silence with for a whole evening and leave feeling we have had the most intresting chat ever?

I believe we have different friends for different times in our lives and we have different friend for different purposes.
When I was 21 I worked with a girl a year younger than me, we worked for a company selling newspaper prescriptions over the phone.
A job neither of us enjoyed but it paid ok and we didnt start work until 14.30 and finished 22.00 mon-thurs and we finished at 19.00 on a friday so life consisted of very late nights drinking coffee and talking and then sleeping til noon.

She was the most intresting person I had ever met.
She was brutally honest, hilariously funny and so street wise I envied her but also looked up to her in an almost adoringly fashion.
But the best thing with her was that she liked me!
She told me I was great and that I could do ANYTHING I wanted to as long as I worked hard for it.
It was beacause of her that I moved to England in the first place, well her and obviously a man....
She had lived and worked in the darkest part of London as a barmaid.
I was gonna do that too...
BUT as I said she was street wise, I wasnt.....
I filled in aplication forms and in the part where you write something about yourself I wrote:
"I am a happy and jolly girl from Sweden...." well......no wonder nobody hired me......who would??

I managed to get a job as a nanny in a nice family and ended up staying on as their lodger for 6 years, they were obviously looking for a "jolly girl from sweden"

Unfortunately I lost touch with my friend, but found her again on facebook last year.
She is married and have a daughter and still looks just as fabulous as she did 10 years ago.
And Im sure she is just as hilariously funny and street wise as she was then.
She probably hasnt got a clue what she did for me and how she affected my life but to me she will always be the most intresting person I ever met.
And she was a friend I desperately needed at that point in my life.

I have decided to move back to Sweden, most of my dreams was brutally shattered early on in my journey which is fine I have had a million other experiences that were just as good if not better, but the question is...shal I call her?
Is it wise to hope that we could take up our friendship again 10 years later?
Or shal I keep her in my heart where she cant change?