Whenever the horse stopped {which it did very often}, he fell off in front; and, whenever it went on again {which it generally did rather suddenly}, he fell off behind. Otherwise he kept on pretty well, except that he had a habit of now and then falling off sideways; and, as he generally did this on the side on which Alice was walking, she soon found that it was the best plan not to walk quite close to the horse.
In this passage from Alice's Adventures in Wonderland and Through the Looking Glass by Lewis Carroll, the horse is described as frequently stopping, which causes the rider to fall off the front. When the horse suddenly starts moving again, the rider tends to fall off the back. Despite these frequent mishaps, the rider manages to keep going for the most part.
Additionally, the rider often falls off sideways, usually on the side where Alice is walking. As a result, Alice finds it wise to keep some distance from the horse to avoid being knocked over or inconvenienced by its frequent falls and sideways tumbles.
