She woke up and realized she had forgotten the definition of the word 'impossible.' She decided it must not have been that important.

CIRCUS HORSES
The beautiful white horses used by the acrobats who ride bareback are one of the familiar sights we love to see at the circus. These are highly trained horses of draft-horse breeds, and they can do wonderful stunts. They are chosen for smartness of gait at a slow, even canter, for broadness of back to give the acrobat a platform on which to stand or sit and for flatness from hip to hip across the croup. A special type of circus horse is the "High School Horse," who is a solo performer. He gives various performances, and he cakewalks or tangos to music. Often he has a lady as his rider. Still another circus horse is the "Liberty Horse." This horse works in a group with other horses, performing acts without a rider, at the direction of the ringmaster.


The history of white circus horses is connected to the development of the modern circus and the role of horses in the circus.

Gibraltar was the name of a white charger that belonged to Phillip Astley, an 18th century horse rider who is credited with founding the modern circus. Astley received Gibraltar as a gift after requesting his discharge from the military in 1766. Astley and his wife, Patty Jones, an accomplished rider, would perform feats of horsemanship together. Astley would ride Gibraltar through the streets of London in his military uniform to attract crowds. The military dress worn by Astley is still reflected in the costumes worn by ringmasters today.

Horses have been a staple of circuses since Astley's time, and their trick riding displays have entertained audiences for centuries.



Philip Astley
In 1766, Astley was presented with a white charger named Gibraltar after he was discharged from the military. Astley and his wife, Patty, performed trick riding and swordsmanship with Gibraltar in London. Astley's military dress is still reflected in the costumes of ringmasters today.

Sir Henry
A white marble circus horse in Windsor Township commemorates Sir Henry, the star of the Hamilton and Sargent New York Circus. The horse's front legs rest on a stone basket that reveals a sleeping pug dog, which is said to have been Sir Henry's constant companion.


The modern circus ring
The modern circus ring was developed in the mid-1700s for circus trick riding. The ring's 42-foot diameter was found to be ideal for horses and riders to perform daring tricks.


https://blog.biodiversitylibrary.org/2015/09/horses-and-history-of-circus.html


The history of the modern circus is deeply rooted in horsemanship. The first modern circuses, which took place during the 18th century, were primarily demonstrations of tricks performed on a horse, first by former soldiers who learned such skills during military training, and later by talented men and women trained from a young age to accomplish acrobatics and other feats atop a horse. In order to teach horses to perform tricks for the circus amphitheater, horsemen relied upon instruction from mentors and in books such as Dr. Sutherland’s System of Educating the Horse, with Rules for Teaching the Horse Some Forty Different Tricks or Feats. . . This 1861 text by Dr. G. H. Sutherland claims to be the first ever published on “Educating the Horse”



Acrobatics on horseback
Acrobatics on horseback began around 1820. Some notable acrobatic feats on horseback include:
Jacques Gautier: In 1825, Gautier performed the first somersault on a horse with a seated return.
John Glenroy: In 1846, Glenroy performed the first somersault with a standing return.
Robert Stickey: Performed the first double somersault.