Friendship
There are very few friends that you run across in life that are true friends... for every, regardless of effort. You know, the kind of friend that you may not talk to for months, and when you talk / get together / whatever, its like you just talked yesterday. No hard feelings about "not keeping in touch", no condemnation, none of that. You're just friends, and you know you'll always be.

I have some friends like that and I'm so grateful. I'm a terrible letter writter, don't do well at keeping in touch, etc. Could be considered a character flaw. But I'm just so happy that I have some friends who love me and who I love, no matter what. And no matter how long its been. Takes all the work out of it. Thanks guys (and girls)!

If you have some friends like that, keep in touch (even if infrequently). They are rare.