Jack and Locke embody the central thesis of Lost: faith versus science, destiny versus free will. Their conflict begins at the caves versus the beach, escalates through the hatch and the button, and reaches its peak when Jack leaves the Island while Locke stays. The tragedy is that Jack ultimately becomes a man of faith -- but only after Locke is gone. Jack's final act on the Island mirrors Locke's lifelong belief that the Island is special and worth protecting. Locke was right all along, and Jack spent the entire series learning what Locke knew instinctively.

1. S1E5
   White Rabbit

   Jack and Locke's first philosophical clash. Locke tells Jack: "I'm an ordinary man... but I've looked into the eye of this Island, and what I saw was beautiful."

2. S2E1
   Man of Science, Man of Faith

   The title says it all. Jack refuses to press the button; Locke insists it matters.

3. S2E19
   Lockdown

   The blast door map reveals Locke has been pursuing the Island's mysteries far deeper than anyone knew.

4. S3E23
   Through the Looking Glass

   Jack leaves the Island. Locke stays. Their paths diverge completely.

5. S6E14
   The End

   Jack becomes the Island's protector -- fulfilling Locke's vision, not his own.

Season 1: uneasy respect. Season 2: open conflict over the hatch. Season 3: competing visions for the survivors' future. Season 4: Locke stays, Jack leaves. Season 5: Locke dies trying to bring Jack back. Season 6: Jack returns as a man of faith -- the very thing Locke always wanted him to be. The Man in Black uses Locke's body, making their final confrontation a battle against a corruption of everything Locke believed.