Note 1 at 1 Cor. 9:7: Paul uses a series of illustrations to strengthen his point (vv. 4,6) that he had the right or power to derive his living from the gospel if he wanted to. Soldiers don't have to maintain themselves. All their needs are met by the government. Those who work in vineyards get to eat freely of the fruit they are harvesting. A shepherd gets to eat the milk from his flock. In any kind of profession a worker has the right to his wages. Therefore, it is right for a minister to live from the proceeds of preaching the gospel.