Question: Who is reported in some ancient sources to have been a philosopher who was the earliest Greek to develop the theory of atomism, who had a daughters were sought by he jealous murderer of Castor? 
Sentence (from "Lynceus (Argonaut)"): Idas and Lynceus murdered Castor because they all (along with Polydeuces) sought Phoebe and Hilaeira, daughters of Leucippus (who was also Idas and Lynceus' uncle in some versions).
Relevant evidence: No