Theory:

     It is sometimes said that fire is a good servant but a bad master. It only means that fire is very useful as long as it is kept under control.
 
     For instance, we use it to cook our food, warm our homes in winter and to generate electricity. But, on the other hand, if fire gets out of control it can be very dangerous. Each year thousands of homes and shops are damaged by fire. Vast areas of forest are also destroyed and hundreds of people are killed or injured.
Explanation:
 
Now that we know that fire can be created using the three elements such as fuel, oxygen, and heat, we should also learn how to stop or control it. Fire is essential in our day to day life. It is used to cook our food, light up our homes during power-cuts, warm homes and buildings in the colder regions, and to produce electricity.
 
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Fire is essential in our day to day life
 
However, fire is useful only as long as we know how to control it. As the saying goes, fire is a good servant but a bad master. So how can you control a fire? Or rather, what does it mean when one talks about controlling fire?

Okay, let us look into a scenario. Imagine it is nighttime and there is a power cut at your place. You light a candle. And when the power comes back, you blow it off. So, you can light it and switch it off as you wish. This is what controlling means. This is when the fire is your servant.
 
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Fire is useful when you know how to control it

However, think of a situation where there is a fire that you cannot put off. What happens when the fire keeps spreading and you cannot stop it? It starts destroying things and lives. This is when the fire turns into a master.
 
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Fire is dangerous when it becomes uncontrollable

Hence, if fire gets out of hand, it can become deadly. Every year, fire goes out of control and destroys thousands of buildings, homes and livelihood, vast areas of forests, and hundreds of human lives.
 
So, it is crucial that we learn not only how to start a fire, but also how to control it.
 
Meanings of difficult words:
 
No.
Words
Meanings
1
ServantAs in someone (or something) who is there to help you with daily chores, usually someone who is under your control or below your rank
2
MasterA person (or a thing) who has complete control of something
3
GenerateProduce
4
Vast
Of very great extent or quantity
Reference:
National Council of Educational Research and Training (2007). Honeycomb. Fire: Friend and Foe (pp. 114-118). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.