One of the cousins asked for an alarm clock for the day they were flying out and I realized how long it had been since I used one. She was surprised when I told her that basically I got up when the dogs woke me, and said "So you don't have a schedule?"
I said "no, I guess not", but realized later that the right answer is: "yes, it just doesn't involve machines". Between the light coming in the windows and the dogs' sense of, well, hunger and wanting to go relieve themselves, we have a pretty predictable schedule, appropriate to our lives.
So "time is ... an art of observation" -- yes, I'll second that.