The attack occurred on Hitler's birthday, which led to speculation in the media. Some people, such as Robyn Anderson, who knew the perpetrators, stated that the pair were not obsessed with Nazism nor did they worship or admire Hitler in any way. Anderson stated, in retrospect, that there were many things the pair did not tell friends. In his journal, Harris mentioned his admiration of what he imagined to be natural selection, and wrote that he would like to put everyone in a super "Doom" game and see to it that the weak die and the strong live. On the day of the massacre, Harris wore a white T-shirt with the words "Natural selection" printed in black.