Back in the old days, if an Orthodox Jew immigrated to the United States, his or her children were almost guaranteed to drift away from Orthodoxy. In the old country, it was said that in America, “even the rocks are treyf.” Fortunately, as the past fifty years demonstrates, there is no such curse on American soil. But there is one place in the world where the ground itself can be ritually impure: the land of Israel.
In today’s parsha, we read the law of the leprous house: “When you enter the land of Canaan that I give for you to possess, and I place a leprous disease on a house in the land of your possession…” (Leviticus 14:35). As the Sefer ha-Chinuch points out, this implies that only a house in land allotted to one of the tribes of Israel can be subject to the disease. The text goes on to say that when a house is confirmed to have leprosy, its stones have to be taken out of the city and put in a makom tamei, a ritually unclean place (14:40). In the entire Tanakh, the phrase makom tamei only appears in this parsha: Rashi interprets it (s.v.) to mean: “A place which ritually clean things do not touch; the verse teaches you that these stones cause the ground to be impure [even though normally, the ground is never subject to ritual impurity] while they are there.”
This is a halakhic application of a principle that appears over and over again in Torah: the sanctity of the land of Israel is a two-edged sword. Just as living in Israel gives a Jew opportunities to perform mitzvot that can’t be done anywhere else, failure to live up to God’s standards can subject one to penalties in Israel that aren’t risked anywhere else. In the next parsha, God warns the nation: “Don’t let the land vomit you out from your defilement of it, the way it vomited out the nation that preceded you” (18:28). You never heard anyone worrying that their sins against God would get them vomited out of North America.