Final answer:
David Halperin notes that 'Identity' and 'orientation' are common to modern understandings of sexuality but were not concepts in classical societies.
Step-by-step explanation:
According to David Halperin, two elements common to our modern understanding of sexuality that were absent from classical understandings are Identity and orientation. Classical societies did not have categories equivalent to 'homosexual,' 'bisexual,' or 'heterosexual,' which indicate a person's sexual identity and orientation, as understood nowadays. In contrast, contemporary cultures often define sexual orientation as a core aspect of one's identity, shaping personal expressions and sociocultural interactions.