The presocrats are a set of philosophers of the most significant for me. Of them I have devoted some attention to Heraclitus, particularly for his fragmentary writing. An aphorism that has been badly translated is very repeated, which in reality, according to the most versed studies, would be: "Diverse waters flow for those who bathe in the same rivers". It is one of the most important, because it expresses his changing vision of things. There is another less well known, apparently simple and very beautiful: "The sun is new every day". I have also been interested in Pythagoras because of the relationship between numbers and music, and the rhythm of the universe. And Zenón de Elea, for the paradox of Achilles and the turtle, so well commented by the contemporary writer Jorge Luis Borges.
Thanks for your synthetic post, @samminator.