Oh what a tiny word to mean so much. Feel emcompasses so many things in the world of horsemanship and like so many things with horses once you start to look for, cultivate and crave feel you will see it in everything that you do. A horseman that has good feel gets along better in life in general, I think.
Feel is that amorphous "thing" that connects your intentions to your horse. With the proper amount of feel you know when your horse is listening to you. You know when your horse has hooked on and tried. You know when he's about to spook, or bolt, or buck. You know when he's about to go from a trot to a canter, or vice versa. Feel is how you communicate your intentions to your horse.
Without a dose of feel you assume one of two roles in your relationship with your horse. Either you rely completely on the horse to get you where you are going like a mere passenger or you become a thoughtless dictator just mindlessly pushing your horse around in the direction you happen to choose to go. Depending on your personal goals and riding ability, these two options aren't necessarily a bad thing but if you are striving to obtain a higher level of horsemanship these two situations aren't likely to help you advance very much either.
When you cultivate feel in your communication with your horse you can read his intentions and reward those intentions when they are building on something that is moving in the right direction. You can also help your horse to read your intentions so that his response is appropriate for the level of energy you are putting into your intentions.
I do an exercise with my horse where I rock them back on their hocks for several steps then rock forward to put them into a canter. The horse is supposed to step right from the back into the canter allowing for maximum collection to be carried forward into that canter. We can do this in a way that is a slow measured back then rock forward into a canter or a fast back that rocks forward into a trot or any combination of those things. My cues to my horse during these exercises really don't change too much, just the energy in my seat and body that communicates to my horse how fast or slow he is being asked to go.
The best part about feel is that it isn't just in horses. Feel is what allows you to open your car door just enough to not whack the yahoo that parked too close to you in the parking lot. It's knowing how much you can crank on that bolt without breaking it. It's what I use daily in my job to know how hard or soft I need to handle tissue during surgery to avoid damage. When you are tuned into feel you'll find it in everything you do. It's a higher sense of awareness between you and your world.
When you forget to use feel is when your horse is likely to either ignore you completely or overreact to whatever you are doing. That's what happens in life too when you just kind of blunder along through without paying attention to what's around. My friend, Ben, calls that a "rolling fracus", and it's a very apt term.
I had never even heard of the term feel as it applies to horsemanship before I was introduced to it a few years ago. Maybe somewhere along the line one of my very capable 4-H leaders had tried to introduce it, but I sure didn't get it. Probably the reason for that is because as a kid and young adult, my main goal with my horses was just to have fun. As long as we both got where we were going with the minimum of arguement I was pretty dang happy with the ride. When I started trying to improve my ability to communicate with my horse because the arguements were getting more and more frequent with my new young horse I had to realize that I had spent a great part of my life in one of the two modes of stagnant horsemanship. I waffled between passenger (on a trail ride) and dictator ( in the show ring).
I used to do quite a bit of gaming. My old Morgan was pretty good at it and honestly, all I had to do was sit still and let him run his course. There was very little communication happening because he just loved to run the patterns and knew them by heart. When I started trying to introduce the gaming patterns to my new young horse I began to realize how spoiled I had been. I figured he'd get it eventually and we practied the patterns slowly at home then raced full speed at the gaming events. Obvisouly we didn't do very well. I couldn't understand where my steering and stopping kept disappearing to whenever we tried to compete. Many people told me I just needed a bigger bit or spurs to really get him to turn around the corner.
Luckily for both me and my horse we didn't go that route. What I decided we really needed was better communication and I started seeking that out. Speed is death on feel. Not that you can't have feel at speed when you get good, but you have to have it very well cultivated and deeply ingrained in your horse before it sticks at speed.
You can't cultivate feel without a better understading of your surroundings and everything in them. When you close the chatter in your brain and tune into the undercurrent of what is going on around you then you can feel. And your horse will thank you for it.