If your car kept getting faster and faster even after you’d taken your foot off the gas pedal, you’d say it was impulsive. There’s so much power and speed but you have to stomp on the brakes to make it slow down. If you pushed the gas pedal to the floor and very little happened, you would say it was non-responsive. Impulsion exists when you can press on the gas pedal and the car responds by moving forward at the appropriate speed, yet when you take your foot off, it decelerates. Impulsion, therefore, is controlled forward energy.
Where go=whoa
A horse that has more go than whoa is impulsive. A horse that has no go, and is all whoa, is non-responsive. A horse who has go and whoa equally, has impulsion. This means it takes less than four ounces [of pressure] to go, to whatever speed you want, and less than four ounces to stop, from whatever speed you are going.
No matter what kind of horse you have, you can enhance impulsion, or ruin it if you’re unconscious of how it works. The Harmony Program explores impulsion as one of its major ingredients. If you’re always having to hold your horse back a bit (or a lot!), or have to urge him to keep going, you cannot have harmony.