We use soap every day.
我们每天都使用肥皂。
At your local supermarket, you can see shelves filled with the stuff (东西).
在你当地的超市里，你可以看到架子上装满了这种东西。
But how did people start using soap and how is it made?
但是人们是如何开始使用肥皂的，它又是如何制作的呢？
The origin of soap
肥皂的起源
The word "soap" comes from the Celtic word "saipo", which means "fat", the material that soap is made from.
“soap”这个词来源于凯尔特语词汇“saipo”，它的意思是“脂肪”，即制作肥皂的原料。
The oldest soap dates back to 3000 BC, when people in Mesopotamia used it for cleaning the wool.
最古老的肥皂可以追溯到公元前3000年，当时美索不达米亚的人们用它来清洗羊毛。
Over the following centuries, soap continued to be used to clean everything but the human body.
在接下来的几个世纪里，肥皂继续被用来清洗除了人体之外的一切东西。
Using soap to bathe
用肥皂洗澡
In the second century, a Greek doctor named Galen wrote about the practice (实践) of using soap to clean the body.
在公元二世纪，一位名叫盖伦的希腊医生记录了使用肥皂来清洁身体的做法。
However, bathing with soap was still not common.
然而，用肥皂洗澡仍然不普遍。
It wasn't until the seventeenth century that soap was used for bathing in Europe, but only the wealthy could afford it.
直到十七世纪，肥皂才在欧洲被用于洗澡，但只有富人才能负担得起。
In the nineteenth century, the soap became available to most people.
在十九世纪，大多数人都能买到肥皂了。
As a result, cleanliness standards improved in many places.
结果，许多地方的卫生标准得到了提高。
How to make soap
如何制作肥皂
One reason that soap has been so common throughout history is that it isn't hard to make.
肥皂在历史上一直如此普遍的一个原因是它并不难做。
To make it, take some alkali (碱) and mix it with fat or oil.
要制作它，取一些碱并将它与脂肪或油混合。
Once everything is mixed, leave the soap in a mold (模具) until it becomes hard.
一旦所有东西都混合好，把肥皂放在模具里直到它变硬。
After 24 hours, it's ready to cut into pieces.
24小时后，就可以将它切成块了。
But you'll need to be patient.
但你需要有耐心。
That's because the soap still needs around two to three weeks to become hard enough before you can use it.
那是因为在你能使用它之前，肥皂还需要大约两到三周的时间变得足够硬。
Easy to make, soap has helped humans stay clean all the way to the modern age.
制作简单，肥皂一直帮助人类保持清洁直到现代。
You could even say it's one of the most important inventions in human history.
你甚至可以说它是人类历史上最重要的发明之一。
英文全文：
We use soap every day. At your local supermarket, you can see shelves filled with the stuff. But how did people start using soap and how is it made?
The origin of soap
The word "soap" comes from the Celtic word "saipo", which means "fat", the material that soap is made from. The oldest soap dates back to 3000 BC, when people in Mesopotamia used it for cleaning the wool. Over the following centuries, soap continued to be used to clean everything but the human body.
Using soap to bathe
In the second century, a Greek doctor named Galen wrote about the practice of using soap to clean the body. However, bathing with soap was still not common. It wasn't until the seventeenth century that soap was used for bathing in Europe, but only the wealthy could afford it. In the nineteenth century, the soap became available to most people. As a result, cleanliness standards improved in many places.
How to make soap
One reason that soap has been so common throughout history is that it isn't hard to make. To make it, take some alkali and mix it with fat or oil. Once everything is mixed, leave the soap in a mold until it becomes hard. After 24 hours, it's ready to cut into pieces. But you'll need to be patient. That's because the soap still needs around two to three weeks to become hard enough before you can use it.
Easy to make, soap has helped humans stay clean all the way to the modern age. You could even say it's one of the most important inventions in human history.