Answer and Explanation:
What Hooper means when he says “the veil is mortal”, is that the things that people hide—their secret sins or hidden nature—is susceptible to death; in fact, it will die one day. However, after death, the veil will be removed.
What Hooper means when he says “There is an hour to come when all of us shall cast aside our veils”, is that a time will come when each person’s secret sins or hidden nature will be removed and exposed before God’s judgement.
