Lenin returned to Switzerland, then went to Germany and lived in the suburbs of Berlin. He spent most of his time in the public library in Berlin, where he studied Marx and Engels' works that he could not see in China, made abstracts and wrote outlines. At the same time, he also paid attention to the study of the workers' movement in western Europe and attended the workers' rally there. Lenin returned to Russia on September 1895 after traveling abroad for four and a half months. He brought back secret Marxist books from abroad and a suitcase with a double bottom. These books are widely circulated among socialists in Petersburg and other cities.