In science, friendship is a type of human chemical bond or chemical association that is step above that in strength of a passing acquaintance association, but below that in strength of an intimate sexual relationship bond.
Overview
In 1841, American philosopher Ralph Emerson, in his essay on friendship, defined the nature of friendship in terms of chemical affinity, in the context of soul mate theory, as such: [1]
“Conversation is the practice and consummation of friendship and great conversation requires an absolute running together of two souls into one, yet it is affinity that determines which two shall converse.”