While a simile states that one thing is like another, a metaphor asserts that one thing is the other, or is a substitute for the other thing. A metaphor asserts a correlation or resemblance between two things that are otherwise unrelated.
ASL emerged as a language in the American School for the Deaf (ASD), founded in 1817. This school brought together Old French Sign Language, various village sign languages, and home sign systems; ASL was created in this situation of language contact. ASL was influenced by its forerunners but distinct from all of them.
The exact beginnings of ASL are not clear. Many people believe that ASL came mostly from French Sign Language (FSL). Others claim that the foundation for ASL existed before FSL was introduced in America in 1817.