In order to clarify the issue, Nechama Leibowitz quoted from several authorities. Rambam wrote that the change from the normal appearance had no parallel in nature, but constituted a sign to warn away from evil talk. He wrote that indulging in evil talk led to the change in the colour of the walls of the house.
Ramban wrote that G-d’s spirit was upon the Israelites when they were in harmony with Him, and it preserved the healthy appearance of their bodies, garments and houses. Whenever a person committed a sin, there would be a discolouration of the skin, garments or house.
Sforno wrote that the idea is that the discolouration was inflicted to draw the victim’s attention to the sins he had committed. When the generations no longer attained such a high level of observance, there was no longer any record of this type of plague.
Alshikh added that the plague teaches us that society should take notice of the first sign of misconduct, however small. In the same way that a disease which begins with minimal symptoms can be stopped if detected in time, so a moral disease in society can be prevented from spreading if immediate steps are taken. Otherwise it will spread throughout the community.
Nechama Leibowitz contrasted Jeremiah’s prophecy of doom and destruction with Isaiah’s message of hope to King Hezekiah. In Isaiah’s time it was still possible to repair matters without resort to drastic means, but in Jeremiah’s time, it was already too late and rebuilding could only occur after destruction. Isaiah could see that when the people were in a state of great distress and fear, so a message of hope was in keeping with their feelings of remorse and repentance. Jeremiah observed that the people were complacent and oblivious to the impending disaster. He foretold the complete destruction of the Temple, and the seventy years of captivity followed by its rebuilding.