"Will you go through this tiny hole and get the treasure that's inside?"
When Link first visits the temple as a child, Nabooru is attempting to get inside of the temple to get the treasure (The Silver Gauntlets), but she cannot fit inside the small hole. She convinces Link to go inside and retrieve them, and once he does, he witnesses Kotake and Koume capturing Nabooru. The bonus to that is Link gets to keep the gauntlets, allowing him to get inside the temple as an adult.
When Link returns as an adult, Link will use the gloves to move around the temple. After traversing numerous enemies and puzzles, Link obtains the Mirror Shield. Link also fights the witch sisters, Twinrova, who are the boss of the Spirit Temple. After defeating them, Link gets a Heart Container and receives the Spirit Medallion. This is the final medallion required for the confrontation against Ganondorf.