Theory:

     The discovery of fire and its uses helped early man to cope with nature better and gradually adopt a settled mode of life. Fire is still worshipped in many parts of the world. Fire is indeed a friend but, as we know, it can be a dangerous enemy once it gets out of control.
Explanation:
 
When the early humans discovered fire, it helped them lead a more comfortable life. It helped them cope with nature. For instance, fire helped them get through harsh winters and had also helped them protect themselves against the wild animals.
 
neanderthals-96507_640.jpg
Early humans using fire

Fire also helped them adopt a settled mode of life. Earlier, people lead the lives of nomads. They never settled down in a single place because they had to meet their basic needs, such as food and shelter. However, fire sheltered them, and as time went by, people learned to cook food before consuming.

shutterstock_1511478152.jpg
Gradually, the early humans adopted a settled mode of life

Though fire is pure science, people from many parts of the world still worship fire.
 
shutterstock_441199573.jpg
The science behind a fire
 
The reason being that fire is both the source of life as well the source of destruction. If not treated with caution, fire will turn deadly.
 
collage (1).jpg
Fire is so powerful that it is worshipped in many parts of the world

Fire can be a great friend, but, when taken lightly, it can be a dangerous foe.
 
Meanings of difficult words:
 
No.
Words
Meanings
1
CopeTo deal effectively with something difficult
2
GraduallySlowly
3
FoeEnemy
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.