Merely to announce what ought to be done without helping motivate people to do it is of little value.
Enveloped in a cloud of dust, the county agricultural agent drove into the farmyard and bounced onto the old farmer's porch. The farm looked pretty much run-down, and the farmer sitting in the creaking rocker did too. The agent, enthusiasm personified, began sharing what he thought were exciting ideas for improving the farm, but the old man stopped him in midsentence. "Simmer down, sonny; I know how to farm twice as good as I'm farmin' already."
Most people are not living even half the truth they already know. They don't so much need to know more as they need to be motivated more. While the principal purpose of illustration is not to excite the emotions, illustrations do help listeners feel the truth. And people mostly do what they feel like doing.