The Cabinet of Souls was, according to the Twelfth Doctor, the centre of Rhodian religion. He that it was the place where the soul of every Rhodian was supposed to go to after dying and a repository for a future paradise. The Doctor concurred with the Shadow Kin leader Corakinus that the Cabinet was a weapon, explaining it as "the power of all that life, crammed down into single specks of light [that] could be enough to destroy an entire species".
Rhodian prince Charlie believed the cabinet was empty, saying its legend was just a nice bed time story for children to make death less scary. Charlie said he kept the empty Cabinet of Souls in memory of his people. However, when he opened the box, he saw a speck of light was in there. He later told Miss Quill that he had to protect his people. (TV: For Tonight We Might Die)