tonight it finally came clear to me the difference between subject and object

subject is what does the thing, object is what suffers the doing upon it

it's kinda upside down compared to "test subject" and "subject matter" because those are the thing you are treating as an object

like, you may be familiar with the notion of "objectifying" something... this is about actions or attitudes that seek to take agency away from the "object"

object is other, subject is self, but it's complicated in context when it is used