The qualities which made him gr8 were:-
1)use of a great brain for writing
2)even after he was not able to speak and was wheel chair bounded as he was suffering from a disease named Lou Gehrig(it is a disease that slowly kills all nerves in the body and eventually kills a person) he wrote books and was a genius in science.
3)n he was d longest known survivor for dis disease(40 yrs)
i knw dis is not an appropriate answer as u want bt i hv given u some points plz try to elaborate them by the help of seeing on d biography of his lifetime history.