In answer to a centurion's earnest request to heal his slave who was desperately sick, Jesus was on his way to the house of the Roman centurion who was in command of the garrison at Capernaum. When the centurion heard that Jesus was coming in person he was amazed, and at once sent messengers to intercept him, protesting that he was not worthy that Christ should go to such trouble. Surely all he had to do was to speak the word, without coming in person, and the sick slave would be healed; for, he said, "I am a man under authority, having soldiers under me: and I say to this man, Go, and he goeth; and to another, Come, and he cometh; and to my servant, Do this, and he doeth it" (Matt. 8:9). What he meant was that if he, a junior noncommissioned officer in the Roman army, could have things done by word of command, without going in person, surely Jesus, the great prophet of Israel, could do likewise.
"A man under authority." At first that seems an odd way of putting it. Why did he not say a man with authority, or a man invested with authority? But this is what he said: "a man under authority." When you stop to think of it, there was sound sense in the way he put it. Above the centurion was the senior centurion, and above the senior centurion, the sixty centurions of the Roman legion. Above the sixty centurions were the six tribunes, and above the six tribunes the two consuls, and—in the imperial system—above the two consuls, the emperor himself. It was because he stood—although the last and the lowest—in this long line of delegated authority that
the Roman centurion was able to give orders and have them obeyed. He could give orders because he received orders. He had authority because he was under authority himself.
In the Greek, the word for 'authority' is 'exousia' ; for `power"dunamis'.
A Government surveyor one day brought his theodolite along to a farm, called on the farmer and asked permission to set it up in a field nearby to take readings. Seeing the farmer's unwillingness to let him enter the field, he produced his papers and explained that he had Government authority for entering the field and could, on the same authority, go anywhere in the country to take necessary readings. Reluctantly the farmer opened the barred gate and allowed him to enter and set up his survey table, but went to the other end of the field and let in the fiercest of his bulls. The surveyor was greatly alarmed at seeing the bull approach, and the farmer from the other side of the gate shouted to him, 'Show him your credentials : show him your authority'. The surveyor had the authority to enter but had not the power to resist the bull. The God- sent evangelist has both authority and power to fulfill his commission. (Matt. 28. 18; Rom. 1. 16)