Themistocles died in 459 BC, probably of natural causes. His reputation was posthumously rehabilitated, and he was re-established as a hero of the Athenian (and indeed Greek) cause. Themistocles can still reasonably be thought of as "the man most instrumental in achieving the salvation of Greece" from the Persian threat, as Plutarch describes him. His naval policies would have a lasting impact on Athens as well, since maritime power became the cornerstone of the Athenian Empire and golden age. Thucydides assessed Themistocles as "a man who exhibited the most indubitable signs of genius; indeed, in this particular he has a claim on our admiration quite extraordinary and unparalleled".