I don’t remember where I got this from (if it rings a bell, please comment), but it seems as profound now as when I heard it the first time. I absolutely believe this:
A true friend is someone with whom you can comfortably occupy the same room without having to speak.
That is, silence is comfortable and not awkward. Speaking is not necessary; speech might even be unwelcome.
One of my favorite memories is the time a few of us met over at a friends’ house for a evening of reading books. By the time I arrived, the kids were in bed, and readers were already sprawled about on comfy chairs with books in their laps. We didn’t talk much, but that was part of the point. Simply being together was enough.