Four-character idiom

There is a special expression called a four-character idiom in Japanese grammar. This idiom consists of four Kanji characters, and only when the idiom consists of four Kanji, it can be called by this special name. Japanese people can understand the difference against other idioms by the sound they heard or the figure they watch.  

When a writer describes his expression, and if the expression is phrased by four-character ideioms, Japanese readers maybe easily understand what the writer express. Because the writer's original expression sometimes is difficult to sympathize exactly same as he intends. That is the reason why ordinary Japanese likes to use four-character idioms rather than describe their own words.

Since their childhood, Japanese people are instilled common understanding in which situation four-character idioms should be used. These understandings are naturally in Japanese people's sensitivity. So, if you choose an appropriate four-character idiom, the receiver seldom misunderstands what you mean to say. Furthermore, if you use these expressions, the listener will take in breeding cultivation in your talk.

We suppose 'English idioms' are also same, if the speaker and the listener have common understanding. Only difference is a special constructional rule. If the idioms aren't constructed with 4 Kanji characters, these are not four-character idioms.

Examples

This means 'direct communication from mind to mind' or 'to understand each other without talking'. It was originally one of 'Zen teachings'.
(i-sin-den-sin)

This means 'emotions' or 'feelings'. These 4 Kanji characters are 'rejoice', 'angry', 'pity' and 'enjoy'.
(ki-do-ai-raku)

This means 'honest and sincere nature' or ' serious and straightforward'. We think this word imply very faithful and loyal people.
(kin-gen-jiitu-choku)

This means 'from the bottom of one's heart' or 'wholeheartedly'. And, 'to be sincere and honest'.
(sei-sin-sei-i)

This means 'one-in-a-lifetime opportunity'. We think it also means mental preparedness for human beings.
(ichi-go-ichi-e)