Similarly thought is a system. That system not only includes thought and feelings but it includes the state of the body it includes the whole of society - as thought is passing back and forth between people in a process by which thought evolved from ancient times.
The thing I care about is my weight - I'm as fanatical about it as a member of Girls Aloud. I weigh myself every morning. I know exactly what I want to be - 82kg - and I try to stick to it.
