一yī目mù了liǎo然rán

Literal: with one glance, everything clear
Figurative: So clear and well laid out that you grasp it the moment you look; obvious at first sight.

Where does 一目了然 come from?

It does not come from a particular tale: it is a very common set phrase. It is built from two blocks, 一目 ("a single glance") and 了然 ("clear, evident"), so that one look is enough for everything to be plain. Today it is used above all for charts, maps, lists or well-organized explanations.

How is 一目了然 used? Two examples

这zhè张zhāng图tú表biǎo做zuò得de很hěn好hǎo，收shōu入rù和hé支zhī出chū一yī目mù了liǎo然rán。
This chart is really well made; income and expenses are clear at a glance.
把bǎ房fáng间jiān整zhěng理lǐ好hǎo以yǐ后hòu，东dōng西xī放fàng在zài哪nǎ里lǐ都dōu一yī目mù了liǎo然rán。
Once the room is tidied up, where everything goes is obvious at a glance.

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