Usage of 如き, 如し, 如く


如き【ごとき】, 如し【ごとし】, 如く【ごとく】 all mean "like/as if/the same as". Is there a
certain way they can be used or are they interchangeable?




These are all different forms of the helping verb ごとし.

They are used differently this way:

  * 如し ⇒ のようだ (used as a verb)
  * 如く ⇒ のように、のようで (used like an adverb)
  * 如き ⇒ のような (used as an adjective)

>   * 目差しは炎 **の如し** ⇒ 目差しは炎 **のようだ**  
>  (his) gaze was as a flaming fire
>   * 海 **の如く** 広い草原を渡る ⇒ 海の **ように** 広い草原を渡る  
>  (we) cross a plain wide as the sea
>   * 馬 **の如き** 速さで走る ⇒ 馬 **のような** 速さで走る  
>  to run with the speed of a horse
>

如く is the 連用形 of 如し:

  * 眼差しは炎の **如く** 、相手‌​を捕えていた。

如き is the 連体形 of 如し:

  * 炎の **如き眼差し** で、攻撃の準備をしていた。 




  * ～(の)如し is used as a predicate. (sounds archaic rather than simply literary)
  * ～(の)如き modifies a noun (i.e., adjectivally).
  * ～(の)如く modifies a verb (i.e., adverbially).

> その動きは蝶の如し。 His movement is like a butterfly.  
>  光陰矢の如し。 Time flies. (lit. "Days and nights are like arrows.")  
>  蝶の如き動きを見せた。 He showed a butterfly-like movement.  
>  蝶の如く動いた。 He moved like a butterfly.

