Gay literature is a collective term for literature produced by or for the gay community which involves characters, plot lines, and/or themes portraying male homosexual behavior. Because the social acceptance of homosexuality has varied in many world cultures throughout history, LGBT literature has covered a vast array of themes and concepts. LGBT individuals have often turned to literature as a source of validation, understanding, and beautification of same-sex attraction. In contexts where homosexuality has been perceived negatively, LGBT literature may also document the psychological stresses and alienation suffered by those experiencing prejudice, legal discrimination, AIDS, self-loathing, bullying, violence, religious condemnation, denial, suicide, persecution, and other such obstacles. Themes of love between individuals of the same gender are found in a variety of ancient texts throughout the world. The ancient Greeks, in particular, explored the theme on a variety of different levels in such works as Plato's Symposium. LGBT themes in mythology and LGBT themes in classical mythology Many mythologies and religious narratives include stories of romantic affection or sexuality between men or feature divine actions that result in changes in gender. These myths have been interpreted as forms of LGBT expression and modern conceptions of sexuality and gender have been applied to them. Myths have been used by individual cultures, in part, to explain and validate their particular social institutions or to explain the cause of transgender identity or homosexuality. In classical mythology, male lovers were attributed to ancient Greek gods and heroes such as Zeus, Apollo, Poseidon and Heracles (including Ganymede, Hyacinth, Nerites and Hylas, respectively) as a reflection and validation of the tradition of pederasty. Homoerotic literature in ancient Rome Though Homer did not explicitly portray the heroes Achilles and Patroclus as homosexual lovers in his 8th-century BC Trojan War epic, the Iliad, later ancient authors presented the intense relationship as such.