In spite of his growing literary interests, Klein's early poetry of the 1920s and 1930s was largely concerned with Jewish themes, including the history of Jews in Western society ("Design for Mediaeval Tapestry"), the importance of religion as a mediating force in modern society ("Heirloom"), and tributes to important figures in Jewish culture ("Out of the Pulver and the Polished Lens," about the philosopher Spinoza). Klein published many of these early works in Canadian and American periodicals, although the Great Depression made it difficult for him to find a publisher willing to accept an entire book. He also published two poems in the 1936 anthology of modernist Canadian poetry, "New Provinces".