How do you say goodbye?

You can, I suppose, tell someone whom you've greeted, chatted with, debated with, shared opinions with, laughed with, seen around all the time that you won't be there when they come back after the summer's over. But what is this sense of loss settling into a quiet niche within me?

I'm sad that I have to go. It's impossible to stay of course, but I feel sad all the same. Because for those whom I've had the fine fortune to know here, I don't know when we'll meet again.