Why did the Spartans not arrive earlier to help the Athenians?

The Spartans did not arrive earlier to help the Athenians during the Persian Wars primarily due to their strict military and religious obligations. They were engaged in their own festival, the Carneia, which prohibited them from taking military action. Additionally, the Spartans were cautious and wanted to assess the situation before committing their forces. This delay ultimately meant they could not assist the Athenians in time for critical battles, such as the Battle of Marathon.