Subject and object are a pair of juxtaposed categories, and each of which can only obtain its own definition in relation to the other. Every material being has an effect on others, namely, the other surrounding beings. In such actions, the one producing, initiating the effect is the subject of the effect, while the one receiving the effect, being acted upon, is the corresponding object of the effect. Since actions between things are mutual, any particular thing is both actor and acted upon, is both subject and object, and thus the distinction between subject and object has a relative character.