How did Plutarch organize the biographies in Parallel Lives?

Plutarch organized his influential collection, Parallel Lives, by pairing a famous Greek hero with a Roman counterpart. These subjects were selected primarily for their similarities in character or career.123

Each pair typically followed a consistent structure:
* Biographical Narrative: A detailed account covering the subject's birth, youth, character, major achievements, and circumstances of death, often enriched with anecdotes and ethical reflections.32
* Formal Comparison: Each pair concluded with a direct, formal comparison between the two figures.13

While Plutarch originally planned to publish these in successive books, the current arrangement is a later reorganization based largely on the chronology of the Greek subjects, who are placed first in each pair. His overarching goal was to provide model patterns of behavior and foster mutual respect between Greeks and Romans. Today, 22 of these pairs survive, alongside four single biographies.312