“Jesus said to them.
Like a flash
εἶπεν δὲ αὐτοῖς Ἐθεώρουν τὸν Σατανᾶν ὡς ἀστραπὴν ἐκ τοῦ οὐρανοῦ πεσόντα
Luke uniquely indicated that Jesus told his 70 returning disciples (εἶπεν δὲ αὐτοῖς) that he had watched Satan (Ἐθεώρουν τὸν Σατανᾶν) fall (πεσόντα) from heaven (ἐκ τοῦ οὐρανοῦ) like a flash of lightning (ὡς ἀστραπὴν). If Jesus and his disciples were making progress that meant that the prince of evil, Satan, was not doing well. Thus, Jesus said that Satan was falling or failing. He would no longer be in the higher heavens. This image of a lightning flash as a falling Satan was very vivid. Would you consider lightning in the sky the falling of Satan?