Here’s our fortieth kotowaza:

四十にして惑わず
(Shijuu ni shite madowazu; “At forty, no doubts”)

Definition:

This extremely optimistic saying asserts that by the time you reach forty years old, your ability to reason is well-developed, your studies have given you a solid grounding in the facts of how the world works, and therefore your path through life is clear, without the need to second-guess your decisions. Because we’re all rational actors who have been given excellent educations, including good sets of mental tools for sussing out and effective pursuing our long-term best interests, right?

Breakdown:

四十 (often yonjuu, but here shijuu) is four tens, i.e. forty. に (ni) is our positional or directional marker and して (shite, pronounced “shee-teh” rather than in the Olde Englishe manner!) is the verb する, “to do,” in conjunctive form. However, in combination the phrase にして can itself be a positional marker. Hence the translation as “at.” 惑わず (madowazu) is an old-fashioned negative form of the verb 惑う (madou) “to be puzzled,” “to have doubts.”

Notes:

This saying also exists as a yojijukugo, 四十不惑.

Today’s kotowaza is attributed to the Analects of Confucius for its ultimate source, which tells you something about the worldview that informs the assertion it makes. It is drawn from a much longer saying that begins at age 15 (with the desire to study) and extends to 70, when one supposedly attains the ability to not wander from the righteous path even while doing whatever the heart desires. Thirty is the year at which the basics are mastered and true study can begin; forty is the year by which confusion and lingering doubts have fallen away.

Some people apparently replace 惑う (madou) with 迷う (mayou, “to lose one’s way,” “to hesitate”), but this is an error.

Example sentence:

「パパ、頭良いね」　「歳のお陰だ。四十にして惑わずというからね、ハハハ」

(“Papa, atama ii ne.” “Toshi no okage da. Shijuu ni shite madowazu to iu kara ne, ha ha ha.”)

[“Daddy, you’re so smart!” “It’s the wisdom of years. They say at forty you’re no longer subject to doubt, ha ha ha.”]