For what thematic purposes does Sinclair continue to insert his authorial voice?

Sinclair's The Jungle is one of the most important examples of early twentieth century muckraker journalism. Taking their name from a term first used by President Theodore Roosevelt, muckrakers sought to expose the corruption within business and government. They did so by publishing articles and books describing, often in horrifying detail, the conditions of corruption and the ways in which it affected the lives of those both directly and indirectly involved.

The Jungle exemplifies this muckraker style in its often gory depictions of life in a meat packing factory. Sinclair writes of how the meat packing industry exploits its workers, many of whom are uneducated and poor. He also gives examples of the unsanitary conditions in which much of America's food was made. Muckraking journalism inspired public outrage and catalyzed a number of reform movements in the early twentieth century.