Why did Louis Braille's own school only adopt braille after he died?

Because of a struggle inside the school, settled in the end by its students. The principal, Alexandre-René Pignier, supported Braille's system and let it be taught, but in 1840 he was forced out by an ambitious younger teacher, Pierre-Armand Dufau, who opposed teaching braille at the school. Another teacher, Joseph Guadet, backed Braille, and the system was reintroduced in 1844. Braille died in 1852, and only in 1854, because of the overwhelming insistence of the blind pupils, did the Institute formally adopt his system.

Braille had lost his sight at three, when an awl glanced off a piece of leather in his father's workshop and struck his eye; by five he was completely blind. At the Royal Institute for Blind Youth in Paris, one of the first schools for blind children in the world, pupils read books made by the founder, Valentin Haüy, who was not blind himself: heavy paper embossed with ordinary Latin letters, traced slowly with a finger. In 1821 Braille learned of Charles Barbier's code of up to twelve raised dots, later called 'night writing.' Its 12-dot symbols didn't fit under the pad of a finger, so in 1824, at fifteen, Braille developed a six-dot version whose letters could be recognized with a single touch.

He published it in 1829, and later extended it to music. 'Access to communication in the widest sense is access to knowledge,' he wrote, 'and that is vitally important for us if we are not to go on being despised or patronized by condescending sighted people. We must be treated as equals.' He also became a full professor at the school by 1833.

After its adoption in Paris, braille spread through the French-speaking world, and by 1882 the advocate Thomas Rhodes Armitage could report that almost every institution in the 'civilized world' used it, except some in North America; schools for the blind in the United States officially adopted it in 1916.