QUOTE : What can Snape do? Tensions between opposing groups of students are so volatile that someone has created an actual explosion in his class, causing physical harm. He can’t know Harry was only trying to create a diversion. He probably thinks Harry wanted to hurt Goyle; any teacher would think that. Dumbledore is no closer to finding the culprit, but Snape must defend against the Dark Arts—he must teach the children to resist the suspicion and hostility that increase in atmospheres of heightened fear. Or, if they cannot resist, he must program defenses into them before the fighting escalates further.