The word 为了 is formed through the fusion of two classical elements: the character 为, which carries a core sense of "to act" or "to be for", and the particle 了, which often indicates a change of state or completion. Their combination creates a new, single conceptual unit where the sense of "acting for a purpose" is crystallized and finalized, shifting from a literal action into a fixed prepositional meaning denoting intention or purpose. This is not a simple sum of parts but a lexicalization where the two characters have merged over time to express a single, relational idea.