Luke does not say why Jesus asked. What the question does in the story is bring the truth into the open. The answer, "Legion," showed that this was not one spirit but "many devils" (Luke 8:30). Matthew Henry says, "They either were, or at least would be thought to be, a legion, formidable as an army with banners." The answer made plain how great the bondage was, and so how great the deliverance would be (Luke 8:35-36).

The answer came at once: "Legion: because many devils were entered into him" (Luke 8:30). In Mark the spirits say it themselves: "My name is Legion: for we are many" (Mark 5:9). Then "they besought him that he would not command them to go out into the deep" and begged to enter a herd of swine; "And he suffered them" (Luke 8:31-32). The herd ran down into the lake and was choked, and the man was found "clothed, and in his right mind" (Luke 8:33, 35).

"Legion" was a Roman military word. Barnes explains that "the name legion was given to a division in the Roman army," and that the word came to signify a large number without a fixed count. Henry says those who possessed the man "called themselves Legion," because many devils were entered into him (Luke 8:30).

The devils begged not to be sent "into the deep" (Luke 8:31). Gill understands this as the bottomless pit, where other evil spirits are held in chains of darkness. Matthew's account has a related fear: "art thou come hither to torment us before the time?" (Matthew 8:29).

The answer "Legion" sounds like an army, but the army could not move without Jesus' permission. The devils "besought him" twice (Luke 8:31-32), and they left only when "he suffered them." However many they were, Jesus was more than enough. Henry's picture of a force "formidable as an army with banners" only makes His authority clearer.

The answer Luke records is not the man's own name but "Legion." By the end of the story he is no longer described by what held him. He is the man "out of whom the devils were departed," sitting at Jesus' feet, and he becomes a witness who "published throughout the whole city how great things Jesus had done unto him" (Luke 8:35, 38-39).