The agent doing the examination of an object.

Alone amongst terrestrial matter humans are both subject and object. We are biological, and hence physical, beings, and under the purview of biological and physical laws. We are also conscious beings with purpose and agency, traits the possession of which allow us to understand the kinds of creatures we are and to design ways of breaking the constraints of biological and physical laws. We are, in other words, both inside nature and outside it.

See objectivesubject, and subjective.