Herakles is but the humanized double of Helios. It is from the sun he borrows his tireless energy. As the young sun he fights with Hades the setting sun at Pylos.
Harrison argues that Herakles is fundamentally a solar Year-Daimon whose mythological adventures encode the daily and seasonal movements of the sun.
, Themis: A Study of the Social Origins of Greek Religion, 1912thesis