Page "Robert A. Heinlein" Paragraph 65

Heinlein grew up in the era of racial segregation in the United States and wrote some of his most influential fiction at the height of the US civil rights movement.

His early juveniles were very much ahead of their time both in their explicit rejection of racism and in their inclusion of non-white protagonists — in the context of science fiction before the 1960s, the mere existence of non-white characters was a remarkable novelty, with green occurring more often than brown.

For example, his second juvenile, the 1948 Space Cadet, explicitly uses aliens as a metaphor for minorities.