Bruno Latour writes, An “actor” in [actor-network theory] is a semiotic definition -an actant-, that is, something that acts or to which activity is granted by others.
Algirdas Julien Greimas (1917–1992), professor of semiotics, is widely credited with producing the actantial model in 1966.
The concept of actant is important in structuralism of narratology to regard each situation as the minimum independent unit of story.
To contend with the overlapping situations present in all narrative structure, she called the potential actant shifts not "change", but "transformation."
[5] Since ancient times, astrology considered and analyzed the position of the persons concerning a situation with the symbols of the celestial objects and constellations.