Contrary to the popular beliefs, Old Japanese (and proto-japanese) had the active-passive alignment instead of the accusative-nominative aligment it (supposedly) has today.
Transitivity of the verbs of change (henka dousi)
Most verbs of change have two variants, one being intransitive (representing an action of being changed/impacted), and one transitive (representing an act of causing something/someone to change). Here are some examples:
| original verb | intransitive form | transitive form | meaning |
|---|---|---|---|
| hajimu | hajimaru | hajimeru | to start |
| nigu | nigeru | nigasu |
Having this duality might seem a bit odd, given that old-japanese had only one form for these verbs. Given old japanese tended to omit case-marking particles, it might seem odd not to know if the noun is being the subject or the object of an action
The active-passive model
- Agent - the active doer of an action, someone who makes the impact
- Patient - the passive receiver of an action, someone (involuntarly) impacted by the action
On the surface, it might look like these are just synonyms for subject and object, however they represent semantic function instead of syntactical one. As an example, making a sentence use passive voice changes the subject, but it doesn't change the agent
The key piece of info is that verbs of action have an obligatory agent and optional patient, while verbs of change have an obligatory patient and optional agent.