Political Fragments of Archytas, Charondas, Zaleucus + Hierocles

In a similar manner, of that part which is auxiliary, powerful, and efficacious, one part is of a governing nature, another is defensive, and the remaining and greater part is soldierly and military. It is from the governing part that the leaders of armies, the commanders of cohorts, the officers of bands, and the vanguards are derived, and universally all those who rank as leaders. The vanguards consist of those who are most brave, most impetuous, and most daring.

Regarding the third part—which is engaged in manual occupations and laboring to procure the necessaries of life—one part consists of farmers and those employed in cultivating the land. Another part consists of artisans who produce such tools and machines as the needs of life require. The final part is engaged in travel and trade, exporting to foreign regions such things as are in surplus.