While Superman has made a tremendous impact on the world through his never-ending battle for Truth, Justice, and the American Way, the fact remains that injustice and suffering continue to plague human society. Some have wondered why Superman, with his great powers and intellect, doesn't just use his Kryptonian abilities to cure all of society’s ills instead of putting criminals in jail. It turns out, he could - just not alone.
In truth, Superman has revealed that he’s very careful not to interfere too closely with humanity’s development and prefers to function as a source of inspiration for others. At one point, however, the Man of Steel saw fit to allow other Kryptonians to do what he couldn’t – cure cancer and other Earthly diseases.
This touching story took place in All-Star Superman #10, which saw Superman suffering from a terminal condition that was slowly killing him. As his white cells began dying, the Man of Steel knew he needed help, and he turned to an unlikely source – the miniaturized citizens of Kandor! Once a thriving Kryptonian city, Kandor was shrunken by the alien conqueror Brainiac for his collection of bottled societies. Superman managed to retrieve Kandor but couldn't reverse the shrinking process, forcing him to keep the bottled city in his Fortress of Solitude.
As he neared the end of his life, Superman came up with an innovative solution for Kandor – take the city to Mars and release the citizens where the rays of the yellow sun granted them the power to create a new society. Since some of Kandor’s leaders felt their society would be polluted by interactions with Earth’s human culture, Mars offered a place where size literally didn’t matter.
While most of Kandor settled in its new home, some Kandorians elected to stay behind on Earth to aid Superman. Still miniaturized, the doctors of the Kandor Emergency Corps entered Superman’s bloodstream and used their medical knowledge and superpowers to prevent Superman’s white blood cells from self-destructing, Although their efforts helped Superman function well enough to complete his labors for the day, they were still unable to save his life.
Even so, Superman felt the Kandorian heroes had shown they were willing and able to accomplish an even more monumental task – save humanity in his absence. Returning to a children’s cancer ward where he makes regular visits, Superman states that human diseases will be no match for Kandorian knowledge and powers. Promising the children that they will all be going home soon, Superman leaves them in the care of the microscopic scientists, who should be able to cure their illnesses.
Of course, whether or not the Kandor scientists went on to cure all of humanity’s medical ills is a matter for debate. Superman knew that humanity needed to progress at its own pace, and the Kandor Emergency Corps likely had its own directives against interfering too much in human society. Still, Superman always hoped that Kryptonian and human societies could co-exist peacefully and for mutual benefit – and the fact that he left Earth’s future in the hands of Krypton’s best and brightest bodes well for the world’s future in the timeline of All-Star Superman.