In Act III of "The Crucible", Danforth says to John Proctor, "We burn a hot fire here; it melts down all concealment." How does this passage reinforce the play's theme, as suggested in the title?

John Proctor is telling Danforth how everything the girls say and do is pretense. He has Mary Warren with him and she tells Danforth as well, Danforth asks Mary if the other girls are also pretending and Mary answers, "Aye, sir." Parris tells Danforth, "Excellency, you surely cannot think to let so vile a lie be spread in open court!" Danforth says, "Indeed not, but it strike hard upon me that she will dare come here with such a tale. Now, Mr. Proctor, before I decide whether I shall hear you or not, it is my duty to tell you this. We burn a hot fire here; it melts down all concealment." Proctor, "I know that, sir."