The form body is impure

Where do all the waste and wastewater produced over a lifetime by all sentient beings on Earth ultimately go? According to the law of conservation of matter, or the law of conservation of mass, this waste and wastewater also has a source—where does it come from? When beings are reborn onto Earth in later lives, where does everything they consume and use come from? After being used, it becomes waste, wastewater, and garbage—where does that garbage go?

Quite a few people have a compulsion for cleanliness and love being very clean, but where does the water they drink daily come from? What kind of water is it? Where does the food they eat every day come from? What ingredients does it contain? Where does the garbage left over after eating ultimately go? Every country has sewage treatment plants and waste recycling stations—what are the water and garbage processed by factories used for? For example, if you pour a basin of dirty water into the ground, how does that water disappear from the ground? Where does it disappear to? Wastewater and dirty water can only partially evaporate; the other part remains on Earth, being recycled and reused by people, and even drunk. The part that evaporates returns to Earth when it rains, and is used again. In short, these materials are used again by humans in various forms, entering the physical body.  

Therefore, contemplating the body as impure is very easy to observe: both inside and outside the body are impure. Although many people have a compulsion for cleanliness, no one is actually clean. Sentient beings crave and love other physical bodies, and even eat meat—there is truly no reason for this; the flesh body is far too filthy. Whatever garbage you produce in this life, when you return to Earth in a future life you will have to consume that garbage again, and may even make your descendants consume it together with you. Sentient beings all love life and are very fond of the physical body and the six sense objects, but these are all extremely filthy—what is there to like about them? Or perhaps they are fond of a certain kind of mind, but the mind is also filthy and defiled, full of afflictions—what is there to like about it?