"Sooner or later we're all someone's dog"

This quote by Terry Pratchett speaks with the idea that, no matter who we are, we all have someone in our lives who has power over us. We might be the master of our own fate, but there are constantly people who have authority over us in some method. Whether it's a moms and dad, an employer, or an instructor, all of us have somebody who can influence our choices and our lives. This quote is a suggestion that, no matter how independent we might be, we all have someone who can manage us in some method. It's a tip to be mindful of the power characteristics in our lives and to be aware of how our decisions can be affected by those around us.