what is the origin of this phrase. The only thing that i can think of is that maybe races were called tricks once, but failing that how did the phrase come about?
I know that a one-trick pony refers to a horse that can only be taught one trick, i.e., it can learn to kneel or something, but can’t be taught to count to ten, or do long division. What it means is someone who can only do one thing well, and is unable to learn anything else.
Just a WAG, but “back in the day” there were a lot of circuses or shows where horses were trained to do specific things. In particular, I’m thinking of the diving horses here. At the end of their careers as divers (if they were injured or too old, or when the practise stopped) these horses were pretty much useless since it was all they had ever learned to do. You’d have a hard time getting a harness on them since they’d likely never had one, or even a saddle. I imagine getting a bit in their mouths would be a hassle too, and not worth the effort of trying to teach an old animal something new, hence the phrase. Even today, IIRC, some racehorses have to be trained pretty hard to teach them to lead off and ride on the right lead, since races are all run on the left. It can be done, but it;s hard. Kinda like teaching an old dog new tricks.
European racehorses swing both ways.