ezio drew comfort and satisfaction from the fact-and he shared this dark knowledge with machiavelli and leonardo alone-that the apple of eden , which had fallen into his care , and which had caused so much anguish and death in the battle for its possession , was buried and hidden deep in the vaults below the church of san nicola in carcere , in a secret sealed room whose location they had marked only with the sacred symbols of the brotherhood-which only a future assassin would be able to discern , let alone decipher .