If you met Aristotle at a party he might inquire if you live the golden mean. This moralist theory is useful to consider characterisation, themes and reader response.
Reader-response theorists believe texts need to have a reader before it can mean anything. They will ask you to fill the gaps and make connections.
At this party, the post-structuralist host serves drinks, muttering “gaps and silences”. Those who are interested in psychoanalytical theory argue that the emotional conflicts between characters are most important for meaning. Meet a post-colonialist and they will be arguing against representation of race and identity with you. The Marxist literary theorist will join in the argument and want to explore the conflict between the privileged and working class characters in the novel you are studying. The feminist theorist will remind you that gender is a social construction and power is shown through relationships. The oldest party guest looks sad, and reminds you to look for genre conventions.
Carrying history books instead of a gift, the sociocultural historicist arrives late.
Whom do you believe? Well, it depends on the text!