一而二，二而一

Chinese

		one; single; a one; single; a; (before verbs) as soon as, once; (before a noun) entire (family, etc.)	and; as well as; but (not) and; as well as; but (not); yet (not); (shows causal relation); (shows change of state); (shows contrast)	two		two	and; as well as; but (not) and; as well as; but (not); yet (not); (shows causal relation); (shows change of state); (shows contrast)	one; single; a one; single; a; (before verbs) as soon as, once; (before a noun) entire (family, etc.)
simp. and trad. (一而二，二而一)		一	而	二	，	二	而	一
Literally: “One then two, two then one”.

Pronunciation

• Mandarin

  (Pinyin): yī ér èr, èr ér yī

  (Zhuyin): ㄧ ㄦˊ ㄦˋ , ㄦˋ ㄦˊ ㄧ

• Cantonese (Jyutping): jat¹ ji⁴ ji⁶, ji⁶ ji⁴ jat¹

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• Mandarin
  • (Standard Chinese)⁺
    • Hanyu Pinyin: yī ér èr, èr ér yī
    • Zhuyin: ㄧ ㄦˊ ㄦˋ , ㄦˋ ㄦˊ ㄧ
    • Tongyong Pinyin: yi ér èr, èr ér yi
    • Wade–Giles: i¹ êrh² êrh⁴, êrh⁴ êrh² i¹
    • Yale: yī ér èr-, èr ér yī
    • Gwoyeu Romatzyh: i erl ell, ell erl i
    • Palladius: и эр эр, эр эр и (i er er, er er i)
    • Sinological IPA ^(key): /i⁵⁵ ˀɤɻ³⁵ ˀɤɻ⁵¹⁻⁵³ ˀɤɻ⁵¹ ˀɤɻ³⁵ i⁵⁵/
• Cantonese
  • (Standard Cantonese, Guangzhou–Hong Kong)⁺
    • Jyutping: jat¹ ji⁴ ji⁶, ji⁶ ji⁴ jat¹
    • Yale: yāt yìh yih, yih yìh yāt
    • Cantonese Pinyin: jat⁷ ji⁴ ji⁶, ji⁶ ji⁴ jat⁷
    • Guangdong Romanization: yed¹ yi⁴ yi⁶, yi⁶ yi⁴ yed¹
    • Sinological IPA ^(key): /jɐt̚⁵ jiː²¹ jiː²² jiː²² jiː²¹ jɐt̚⁵/

Idiom

一而二，二而一

1. one and the same
2. two sides of the same coin