He called him into the Berlin Secession in 1903, featured his work in exhibitions, and encouraged him to sell drawings – and when Zille lost his job as a lithographer in 1910, he encouraged him to live from his drawings alone.
Han kaldte ham til Berlin Sezession i 1903, udstillede Zille's arbejder og opfordrede ham til at sælge tegninger - og da Zille mistede sit job som litograf i 1910, opfordrede Liebermann ham til at leve alene af sine tegninger.