"And it came to pass when Pharaoh sent out the people" (Exodus 13:17). Rebbe Elimelech of Lizhensk reads the entire Exodus story as a map of the soul's struggle against the evil inclination.
Pharaoh (Par'oh) is a name for the yetzer hara, the evil inclination. Its letters rearrange to spell ha-oref—"the stiff neck," the force that makes a person rigid against God. "When Pharaoh sent out the people" means: when the evil inclination releases its grip on a person who has repented. But "God did not lead them by the way of the Philistines"—even after repentance, God is not fully consoled. Why? Because this person "holds the rope at both ends." They have abandoned their worst sins, but not completely.
The Philistines are the proof. They showed Isaac some derech eretz (civility)—Avimelech said, "My land is before you"—but also "envied him." Their goodness was incomplete. So too this half-repentant person: close to returning to old patterns, vulnerable when the war of the yetzer hara intensifies.
"God turned the people by way of the wilderness"—through hitbodedut, solitary contemplation, like the emptiness of a desert. "Sea of Reeds"—through Torah study, for Torah is called a sea. But the complete tzaddik (a righteous person)im (the righteous), "the children of Israel, went up armed (chamushim) from Egypt"—they leave fully equipped, their spiritual armor so strong that the evil inclination has no power over them.
"And Moses took the bones of Joseph"—the great tzaddik takes upon himself the quality of Joseph: atzamot (bones), meaning strength and fortitude in divine service. Each patriarch—Abraham in Kindness, Isaac in Might, Jacob in Splendor—contributed a different weapon for the battle.