Etymology of 天地無用


> WWWJDIC: [天地無用]{てんちむよう} (exp) (yoji) do not turn upside down

I see this on some cardboard boxes in the context of shipping and handling.
Why is this expression used to indicate "this side up", or where does it come
from?

I can understand that 天 and 地 refer to up and down, but how does 無用 (useless,
futile, prohibited) play a role in this phrase?




Yes, many Japanese wonder why, too.

The truth is that it's an obsolete usage of 天地 (except in this idiom!).
日本国語大辞典 (kind of the OED of Japanese) apparently has a definition:

> **てん‐ち 【天地】**
>
> (...)
>
> **(6)** （─する）上下をひっくりかえすこと。
>
> ＊滑稽本・早変胸機関〔１８１０〕「裾廻しは天地（テンチ）するだよ」

that is, 天地 once meant for "to turn upside down", at least attested on 1810 in
Edo period. Thus, 天地無用 means "must not turn (it) upside down", which makes
(made) great sense.

But since this meaning has dropped from usage and 無用 for "must not" has become
an old-fashioned wording too, [one third of Japanese people end up taking it
as "Don't care about top and
bottom"](http://bylines.news.yahoo.co.jp/fuwaraizo/20141019-00040074/), which
is the exact opposite of the original meaning.




Yes, many Japanese wonder why, too.

The truth is that it's an obsolete usage of 天地 (except in this idiom!).
日本国語大辞典 (kind of the OED of Japanese) apparently has a definition:

> **てん‐ち 【天地】**
>
> (...)
>
> **(6)** （─する）上下をひっくりかえすこと。
>
> ＊滑稽本・早変胸機関〔１８１０〕「裾廻しは天地（テンチ）するだよ」

that is, 天地 once meant for "to turn upside down", at least attested on 1810 in
Edo period. Thus, 天地無用 means "must not turn (it) upside down", which makes
(made) great sense.

But since this meaning has dropped from usage and 無用 for "must not" has become
an old-fashioned wording too, [one third of Japanese people end up taking it
as "Don't care about top and
bottom"](http://bylines.news.yahoo.co.jp/fuwaraizo/20141019-00040074/), which
is the exact opposite of the original meaning.

