It is truth mediated through a person. Dr. M L Jones said, “Preaching is logic on fire!” Richard Baxter said, “I preach as never to preach again, as dying man to dying men”.
Word of God performs the purposes for which He designed it. “As the rain and snow come down from heaven and do not return to it without watering the earth...so is my word that goes out of my mouth: it will not return to me empty but will accomplish what I desire".