Parsha Mitzvot: Shemini: Mitzvah 153 – Concept 461
“Any earthenware utensil into whose interior one of them will fall, everything in it shall become contaminated, and you shall break it, of any food that is edible, upon which water comes, shall become contaminated; and any beverage that can be drunk, in any vessel, shall become contaminated (Vayikra 11:33-34) We are commanded to observe the laws of impurity concerning liquid and solid foods (Rambam, Hilchot Tumat Ochlin – The Laws of Impurity of Food).
Tumah, or impurity, is related to Timtum ha Lev, ‘blunting the heart.’ A person must be ever watchful to those things, behaviors, words, thoughts, or the way he spends his time, that blunt his heart, and cause him to lose his sensitivity to positive spiritual stimulation. If a person finds that he no longer is inspired by a prayer that once fired his soul, he must realize that his heart has been blunted, and search his life to discover what caused the barrier. (Eishel Avraham in the name of Rabbi Moshe Cordevero)
Who is more vulnerable to impurity and such blunting of the heart; the fully formed person, or the one who is yet formed and complete? Only a finished vessel is susceptible to the contamination described in this verse! The fully formed person, who has committed himself to a path in life, is more vulnerable than the one yet formed! (Eitz ha-Chaim)