A bellwether is a person or thing that shows the existence or direction of a trend. It originally referred to a male sheep (also known as a wether) that led the flock, usually bearing a bell.
Ahhh….. My Ataxia definitely gives me predictors of how my Ataxia symptoms will affect me. When I get up from a seated position, I can Immediately tell if I’m going to need to grab hold of one of my strategically placed handrails. Of course I can always depend on my Denim!