Death clouds our hearts and minds; it makes us forget prior relationships. The disciples were full of sorrow because of Jesus' death. They had watched from a distance as his limp frame had been pulled down off the cross. Jesus had been pierced and life had oozed from his side; and along with his life their hopes poured out too. Jesus' death (and, likely, the disciples' own shame at having abandoned him) had sealed their faith and hope in the tomb. So when they saw Jesus again, they didn't have any hope with which to greet him only terror and superstition; they thought he was a ghost (v. 37). Fear and disbelief had seized their minds so that they forgot what Jesus had told them (v. 44). Not that they are the only ones who forget. We, too, forget.