In the 5th century B.C. Socrates pondered, "Suppose that we had no voice or tongue, and wanted to indicate objects to one another, should we not, like the deaf…make signs with the hands, head and the rest of the body?"

Socrates’ words suggest that those with significant hearing loss have found ways to communicate since the beginnings of human civilization. But, even in his acclaimed wisdom, Socrates may not have grasped that there could have been a method to the gestures and nods he apparently observed among those hard of hearing.

It would be another two millennia before an 18th-century French educator harnessed the potential of communicating in signs by creating, in collaboration with others, the French Sign Language (LSF). LSF’s New World cousin, American Sign Language (ASL) took form some 60 years later.

Around 1755, Abbé Charles-Michel de l'Épée took it upon himself to teach two deaf sisters in Paris with the hope of leading them to salvation through the Church.

This was hardly the first attempt at providing deaf people with an education. As described in The Deaf Community in America: History in the Making, the Spanish Benedictine monk Pedro Ponce de León famously achieved success in this field back in the 16th century, paving the way for notable 17th-century teachers including Johann Amman in the Netherlands and William Holder and John Wallis in England.

However, l'Épée differentiated himself from his predecessors by recognizing he could best instruct the sisters—and other deaf people in Paris—by learning to understand their signals. From there, he opened a free public school and published his findings in two books. This was a stark contrast to the well-paid private tutors of the past who kept their methodologies cloaked in secrecy.

L'Épée created what he called "methodical signs," a structured system that established gestures corresponding to both physical objects and forms of syntax including part of speech and verb tense. This comprehensive, if cumbersome system provided a roadmap to conduct lessons, even as the common language that emerged among participants took on a life of its own.

"The students that came to the school brought a couple of things with them," says Geoffrey Poor, professor emeritus at the National Technical Institute for the Deaf and creator of American Sign Language Flashcards. "One was whichever signs they had used with their families before they came to the school, referred to as 'home signs,' and being inventive, they created signs for other things they needed to refer to.

"If you have an idea, if you have a concept, if you have a thing and there is no word for it, somebody will create a word, or a lot of people will create different words and the best one will survive that process," he adds. "So the language that evolved in this school in France was a combination of l'Épée’s methodical signs and the home signs and the stuff that grew out of that cauldron, this organic process of language evolution."

Although l'Épée impoverished himself through his devotion to this marginalized portion of society, his school survived to become the still-standing Institut National de Jeunes Sourds de Paris, and left him with a legacy as the founding father of LSF.

Some 60 years after l'Épée first met the deaf sisters in Paris, a seminary graduate named Thomas Hopkins Gallaudet encountered a similar challenge with the deaf daughter of a neighbor in Connecticut. The neighbor, a prominent doctor, was interested in educational opportunities for his daughter, and he asked Gallaudet to travel to Europe to learn about teaching methods there.

Gallaudet journeyed to London in 1815 with the hope of learning from the faculty of the renowned Braidwood Academy for the Deaf and Dumb, which advocated for the "oralist" method of teaching lipreading and speech. Although he had little luck with Braidwood’s administrators, the American was fortunate to come upon a demonstration given by Abbé Roch-Ambroise Cucurron Sicard, l'Épée's successor as head of the Paris school. Gallaudet accepted an invitation to visit Institut National, and after a few months, he returned to the United States with a deaf former student-turned teacher named Laurent Clerc.

In 1817, Gallaudet founded what became the American School for the Deaf in Hartford, Connecticut. As its first teacher, Clerc introduced a version of l'Épée's methodical signs, adapted to English. And, as with the French school, the students brought their home signs, requiring an adjustment period for both students and teacher as they all learned to understand each other.

There was another important influence on the development of communication within the school: The Massachusetts island of Martha's Vineyard had nurtured a thriving Deaf community for more than a century, and those who traveled to Hartford to attend the school carried with them a fully formed native sign system. Together, the mix of Clerc's methodical signs with the established Martha's Vineyard signage and the home signals used by the other students merged into what became ASL.

Following the success of the Hartford school, other schools for the deaf began opening around the country. However, the oralist method that held sway at the Braidwood academy and in other parts of Europe began gaining popularity in America, and with it came increasing tension between those who advocated for sign language-based pedagogy and those who believed that the development of speech was crucial for deaf people to become functioning members of society.

"There's been a strong movement ever since the beginning of anybody even thinking about deaf education to say, 'No, we're not going to let these people learn sign language—that’s going to exclude them from us, and it's going to exclude them from the benefits of the normal world,'" says Poor. "So there was this big movement to not allow sign language into deaf education and instead insist that deaf people learn to talk as well as possible and speech read."

The oralist tide, led by inventor and elocutionist Alexander Graham Bell, largely succeeded in having ASL eliminated from American schools for several decades beginning in the 1880s.

According to The Deaf Community in America, about 80 percent of deaf students were undertaking oral-based education by 1920. Many schools refused to hire deaf teachers during this period, while students caught using sign language often faced punishment.

And yet ASL survived, in part because deaf students, whether covertly at school or safely away from unsympathetic eyes, continued to converse in a way that came most naturally to them.

"There is no way for a profoundly congenitally deaf person—someone who does not and never had hearing usable for speech—there's no way that a spoken language can provide the communication ability that a visual language can for that person, because the ears don't work but the eyes and the hands do," says Poor. "To get real communication into the brain of a person who is profoundly congenitally deaf, oral means are not going to do it. But that's what people insisted on in these schools for a long time."

The turnaround came when William Stokoe, a hearing English teacher for the deaf at Gallaudet University, started examining ASL from a linguist’s perspective. Thanks to his groundbreaking publications Sign Language Structure (1960) and A Dictionary of American Sign Language on Linguistic Principles (1965), ASL began earning long-overdue recognition as a legitimate language and regaining its status as a proper academic tool.

Today, an estimated 500,000 people in the United States use ASL as their native language, making it the third most commonly communicated dialect in the country. While ASL retains some signs from its French roots, this dynamic language continues to evolve among a tech-friendly generation in ways that would surely be inconceivable to its 19th-century founders.