In relation to / to (之于)

Structure A + 之于 + B，犹如 / 如同 …

之于 (zhī yú) topicalizes the RELATION of A to B and usually sets up a comparison: "what A is to B". A 之于 B is stated first as the topic, then spelled out with 犹如, 如同 or 好比: 兴趣之于学习，犹如引擎之于汽车 = "interest is to study what the engine is to a car". It is a distinctly literary frame, at home in essays and oratory, combining cultured 之 (of) with postverbal 于 (with respect to). It is not used in ordinary speech, where one would say 对 A 来说 or 对于.

Examples

兴xìng趣qù之zhī于yú学xué习xí，犹yóu如rú引yǐn擎qíng之zhī于yú汽qì车chē。
Interest is to learning what the engine is to a car.
水shuǐ之zhī于yú鱼yú，正zhèng如rú空kōng气qì之zhī于yú人rén。
Water is to fish what air is to humans.
诚chéng信xìn之zhī于yú商shāng人rén，重zhòng于yú生shēng命mìng。
For a merchant, integrity weighs more than life itself.
自zì由yóu之zhī于yú艺yì术shù家jiā，犹yóu如rú阳yáng光guāng之zhī于yú花huā朵duǒ。
Freedom is to the artist what sunlight is to flowers.

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

This point and the other 370, with audio on every example, inside Wanyu.