When Bertolt Brecht flees Nazi Germany in 1933 he spends fourteen years in exile where he writes some of his most significant works, among them, Leben des Galilei. In his Leben des Galilei, Brecht explores the relationship between the individual and society. Using the historical Galileo Galilei as context, Brecht elucidates the responsibility that scientists must accept for how their discoveries are put to use. With his Galilei figur, Brecht expresses his belief that scientific advancement should be employed for the societal advancement of the common person. Brecht wrote three versions of his Galilei work, each showing significant parallels to Brecht's experiences during the corresponding time period of his exile. This thesis will illustrate these parallels. It will first show that the Galilei thematic is to be found in the very first years of Brecht's exile. It then deals with the influences surrounding the writing of the first version while Brecht is in Denmark. The second part of the thesis focuses on Brecht's exile in America and the resulting second version of his Galilei work. Here, working with Charles Laughton on an English translation of the work, Brecht's Galilei undergoes a fundamental change. Brecht attempts to alter the positive perception of the first version's Galileo who cleverly outwits the Inquisition and secretly has his work the Discorsi smuggled out of Italy. Brecht now wants to portray Galileo as a traitor of the people, who missed his chance to help the common people overcome the suppression they were subjected to. This change is strongly influenced by Brecht's experiences in America and the dawning of the Atomic Age. The last section of the thesis deals with Brecht's return to Europe and the third version of Leben des Galilei written in East Berlin. This is a result of translating the American version into German and the addition of scenes and individual elements cut from the first version to make it more appropriate for American audiences. Brecht maintains and tries to heighten the negative portrayal of Galileo as traitor of the common people.