Horatius Bonar explores the profound question 'How long?' as expressed in Revelation 6:10, emphasizing its significance in human experience and divine communication. He categorizes the cry into three main dialogues: from man to man, from man to God, and from God to man, illustrating the deep yearning for justice and understanding in a world filled with suffering and evil. Bonar highlights the themes of complaint, submission, inquiry, and expectation in the human cry, while also reflecting on God's long-suffering, admonition, and earnestness in His call to humanity. Ultimately, the sermon serves as a reminder of the hope and faith that believers hold onto as they await God's ultimate justice and redemption.