The story
Today a token might buy a game at the arcade. But the word is very old. In Old English, tācn meant a sign or a symbol, and for centuries a token was also evidence: a piece of proof.
That sense shows up in Shakespeare. In Measure for Measure, written around 1603 or 1604, the Duke hands over a letter and says, “Say, by this token, I desire his company.” The letter is the token. It proves the message truly comes from him.
Put “same” in the middle, and the proof does double duty. By the same token means the same evidence, or the same reasoning, leads to one more conclusion. Shakespeare gives a character the words “By the same token” in Troilus and Cressida, probably written around 1602.
The word token reaches back further still, to an ancient root meaning to show, or to teach. A token, in the end, is something that shows.
The old meaning of token as proof has faded from everyday talk. The phrase kept it safe, like a flower pressed in a book.
