以至于
yǐzhìyū · HSK 7
so...that...
以 (by means of) + 至 (reach) + 于 (to) = reaching all the way to the point that
Stacks three connectors: 以 marks the cause, 至 means arrive/reach, 于 points to a target. Together they trace a chain from a cause down to its extreme result, hence so...that... or to such an extent as to.
以 — phonetic 㠯 (plow/tool) + 人 (person)
Originally a pictograph of a hand-held plow or tool (㠯), later combined with 人 (person) to suggest 'using' something. The core meaning 'to use' extended metaphorically to 'by means of', 'with', and 'because of'. In modern Chinese it functions mainly as a grammatical particle.
至 — arrow 矢 inverted + ground 一
至 is a pictograph showing an arrow (矢) landing point-down on the ground (一), depicting the moment it reaches its target. The original meaning was 'to arrive' or 'to reach,' which extended to 'utmost' or 'extreme' — the point beyond which one cannot go further.
于 — two horizontal strokes 二 + vertical hook 亅
于 originated as a pictograph of breath or sound flowing outward, depicting exhalation through a passage. In oracle bone script it resembled a curved line showing motion or extension. Over time it became a grammatical preposition meaning 'at,' 'in,' or 'to,' losing its original concrete sense.