"If any of these dead (animals) falls on a vessel, it will become unclean.... That article must be immersed in a mikveh...." (Leviticus 11:32)
The topic of ritual impurity is a difficult one. This impurity is not a tangible entity; it cannot be seen or felt. It is a 
The Torah teaches that purification is attained through immersion in a natural spring or a ritual bath.
spiritual contamination, the result of association with death. The Torah teaches that purification is attained through immersion in a natural spring or a ritual bath (mikveh) filled with rainwater.

The Torah teaches that purification is attained through immersion in a natural spring or a ritual bath.
spiritual contamination, the result of association with death. The Torah teaches that purification is attained through immersion in a natural spring or a ritual bath (mikveh) filled with rainwater. Why immersion in water?
A Lesson in Estrangement
The story is told of a wealthy American Jew who decided to visit one of the leading Torah scholars of his generation. Upon arriving at the rabbi's home, the visitor was shocked to discover that the renowned scholar lived in a simple house, with a dirt floor and shabby wood furnishings. Anxious to help the rabbi improve his living conditions, the guest suggested that it would be more becoming for such an eminent scholar to have more respectable furnishings, and he would be more than happy to pay for all expenses.
The Torah scholar turned to his guest: "And tell me, where is your furniture?"
"My furniture?" responded the American Jew, baffled. "Why, I am only a visitor here. I don't travel with all my belongings."
"So it is with me," the rabbi replied. "I am only a visitor here in this world...."
The act of immersing in water, Rabbi Avraham Yitzchak Kook taught, contains a profound psychological lesson. All immoral deeds, all flawed character traits, and all erroneous opinions - they all stem from the same fundamental mistake: not recognizing that our life in this world is transitory. Here, we are only visitors. Whatever we find here should be utilized for its eternal value.
When we immerse ourselves in water, we are forced to recognize our existential estrangement from the physical universe. How long can we survive under water? The experience of submerging drives home the realization that our existence in this world is transient and that we should strive towards more lasting goals.
Tents and Natural Springs
The sages (Berachot 16a) hinted at this insight when they compared the effect of Torah study to that of a purifying spring: "Why did Bilaam (Numbers 24:6) compare the tents of Israel to streams? This teaches us that just as a spring raises one from impurity to purity, so too, the tents [of Torah learning] raise one from the state of guilt to one of merit." 
Torah study and immersion in water have a similar beneficial effect.


Torah study and immersion in water have a similar beneficial effect.

In what way is learning Torah like submerging in a natural spring?
Torah study and immersion in water have a similar beneficial effect. Instead of focusing only on the material matters of this world, learning the wisdom of Torah raises our aspirations to eternal values. For this reason, the sages used the expression "tents of Torah." Why tents? A tent is the most transient of homes. This phrase emphasizes the quality of Torah that, like a purifying mikveh or a natural spring, makes us aware of the transitory nature of the physical world.
[Adapted from Ein Ayah vol. I, p. 74; Gold from the Land of Israel, p. 190]