Where did Sigmund Freud get the term id?

Sigmund Freud’s original term for the unconscious mind was not id but es, the indefinite pronoun it in German.

Freud borrowed that term from a physician, Georg Groddick, who in turn had borrowed it from his teacher Ernst Schweninger.

As Freud’s ideas became popular in English-speaking countries, translators felt that simply calling the unconscious it was too vague and unscientific.

They replaced it with its Latin translation, id.