Running rivers makes you feel that every time you have a clean run, it is by the grace of a more powerful force and at anytime, something different could happen and surprise you.
You want another chance to find out more about that river, that rapid. The chance to see if you could ever run it with the full and true knowledge of it. But the river changes constantly, and is unpredictable. It looks different and smells different and acts different for any number of reasons. The temperature and turbidity changes and it feels different. Just like a person, it has moods, attitudes. You want to get to know them, to be able to predict, to understand the changes. But, just as with a person, if you know the river you can look at the sky like a face or feel a breeze like a gesture, and know its mood.
These subtleties are the mystery that is so alluring when you do not know a river, and the familiarity that makes you fall in love when you do know it. And just as with a person, when you get to know these nuances and moods you may experience something you don't like. You may resent them. You may feel betrayed, as if the river had made decisions in its fury or fickleness that were gravitational for you and your friends. You want to stay away, but just as a love affair is ruled by intrigue and danger, you cannot. You return perennially, always drawn back by what you do not know of a river, and equally by the magic that you do know.
The rivers become as real as your friends, with all the minutia of personality, deeper the more time you spend with them. A river can inhabit all five senses and can connect you with a watershed, a continent, a natural pattern, a journey and an endless supply of metaphors. Collectively it is the most powerful force, and individually the most intimate of companions. You feel that you know a river, and you feel that it knows you.
But, you remind yourself as you grasp the hugeness of its scope: the river's greatest gift is to remind you to be humble. You can never truly know it, and it does not remember you.