But I digress.
This particular day, my thoughts drifted to the lovely posting trot my horse and I were doing - at times on the correct diagonal; at times, not. Cue all the hushed chatter about being on the wrong diagonal on purpose... "why in the world would I want to ride on the wrong diagonal??" And maybe, just maybe a small few of you might follow with, "why do I need to be on a diagonal to begin with? Why does that matter?"
Many of you - if you've ever ridden english or learned how to post the trot - learned the following (or similar) rhyme: "rise and fall with the leg on the wall." For those unfamiliar, there are two phases to posting the trot - the rise phase, where we use the moment of suspension, or bounce in the trot, to propel our bodies upward; and the sit phase, when we return to the saddle, only to rise again immediately. All this is done in rhythm with the horses' movement, so that we're in sync, and always - we're taught - with the diagonal pair of the inside hind and outside front legs. But WHY??
Don't know which leg you're moving with? Try this:
Notice in the following series of photos - when learning to see which diagonal you're posting with, establish a good posting trot, then go ahead and look down at your horses' shoulders. You want to eventually get proficient with feeling which diagonal you're on, but for now you will benefit from seeing what you're doing. Disclaimer: this will take you a while to pick this up; having someone on the ground who can confirm whether you're on the right or left diagonal will be extremely helpful; even better if you can do this on a lunge line, where your attention can be zeroed-in on just this observation.
In this first photo, see the blue line just in front of my horses' withers? If you direct your vision generally there, you should be able to watch both shoulders move forward and back (marked by the black circles)
Notice the next picture, the right shoulder/leg is moving forward, while the left shoulder/leg is moving back; and we have the opposite in the second photo.
Give it a try! I hope this was helpful, and if so, please let me know in the comments below!