I think we can learn a thing or two about grudges from our horses. Horses don't hold grudges. But they do have associative memories. You find this when you bring a horse to a location where they have had a bad experience or perhaps something scared them when it looked a certain way on one particular day, but the next day it looks completely different. Keep in mind also that a horse has monocular vision - meaning that they can see with each eye separately. This allows the horse to watch in front of him with one eye and in back of him with the other. This is especially useful when watching for predators.
When a horse sees movement using monocular vision, he will usually turn his head to see with both eyes - switching to binocular vision (to focus on the moving object). When a horse switches from monocular vision to binocular vision, this causes objects to jump and distort - until focused on again. This may cause, or at least explain why horses will occasionally unexplainably spook.
So the next time your horse spooks or misbehaves, understand that it is not his way of holding a grudge against you, he is not capable of that. Understand instead how the mind, eyes, and memory of the horse work - they all work together to keep your horse safe from predators. Remind yourself of these things, be forgiving, and you will improve your relationship with your horse.
PS...(these same things apply to human relationships)
When you forgive you don't change the past, you change the future.
Horsewoman, mother, wife, sister, friend...Self Proclaimed Horse Show Fashionista! After 40+ years in the horse business..I've picked up a trick or two, but more importantly: I am still learning!