A few dealings with student dissenters taught me (too late to help them, I'm sorry to say) that my silent disgust did not necessarily teach them. It often created distance. Unexplained indignation is not always communication. True, silence in some circumstances is a powerful reprover, but not in other situations. To withhold deserved reproof, and the reasons therefore, may be to withhold a warning that is urgently needed. Reproof is often a last railing before an erring individual goes over the edge of the cliff.