"Legilimens" Snape and Dumbledore pointed a wand at each of them, saying the words together. Draco felt his mind slacken as Snape's spell hit him hard. Draco was not powerful enough to keep up the wall and so every thought came rushing to the forefront of his mind. Snape ignored them all and went to the very back, where hazy memories of childhood and beyond seemed to lay dormant. He took the last hour of memory and closed it into a wooden chest which he then padlocked, like a Russian doll the chest was encased over and over by a multitude of chests with small unimportant memories between each layer. A trick Bellatrix had tried to teach him. "Give a small memory, something insignificant to get them off the trail."  Snape seemed to be using that same technique now, which raised the question of how anyone could not see it for what it was. But as the chests stacked over and over, his mind started to forget what it was he needed to hide.