Theory:

1. THOUGH the house and grounds belonged to my grandparents, the magnificent old banyan tree was mine — chiefly because Grandfather, at sixty-five, could no longer climb it.
 
2. Its spreading branches, which hung to the ground and took root again, forming a number of twisting passages, gave me endless pleasure. Among them were squirrels and snails and butterflies. The tree was older than the house, older than Grandfather, as old as Dehra Dun itself. I could hide myself in its branches, behind thick green leaves, and spy on the world below.
 
3. My first friend was a small grey squirrel. Arching his back and sniffing into the air, he seemed at first to resent my invasion of his privacy. But when he found that I did not arm myself with catapult or air gun, he became friendly, and when I started bringing him pieces of cake and biscuit he grew quite bold and was soon taking morsels from hand. Before long, he was delving into my pockets and helping himself to whatever he could find. He was a very young squirrel, and his friends and relatives probably thought him foolish and headstrong for trusting a human.
 
4. In the spring, when the banyan tree was full of small red figs, birds of all kinds would flock into its branches: the red-bottomed bulbul, cheerful and greedy; parrots, myna and crows squabbling with one another. During the fig season, the banyan tree was the noisiest place in the garden.
 
5. Halfway up the tree I had built a crude platform where I would spend the afternoons when it was not too hot. I could read there propping myself up against the tree with a cushion from the living room. Treasure Island, Huckleberry Finn and The Story of Dr Dolittle were some of the books that made up my banyan tree library.
 
6. When I did not feel like reading, I could look down through the leaves at the world below. And on one particular afternoon I had a grandstand view of that classic of the Indian wilds, a fight between a mongoose and a cobra.
Explanation:
 
The story was written by a writer Ruskin Bond. He was famous for his literary works in children's literature. The author narrates a fight between a cobra and a mongoose, which he had witnessed as a young boy while sitting atop a banyan tree at his grandparents' house. The banyan tree is older than the author's grandfather. While the banyan tree is the oldest, it is also the biggest tree in the garden.
 
Big_Banyan_Tree_at_Bangalore.jpg
*Banyan tree
 
Even though the garden belongs to his grandfather, the banyan tree belonged to the author as grandpa couldn't climb the tree as he was sixty-five years old. The banyan tree has long branches which touch the ground, and they occupy a large space in the garden. The tree was as old as the city where it was planted - Dehradun. Small creatures like squirrels, snails, and butterflies were living on its branches. During summer, the boy enjoyed the company of the Banyan tree as not only did it serve as his reading spot, but also a hiding spot during times of need.
 
shutterstock_21542698.jpg
Butterflies and snails

Our author became friend with a small grey squirrel. At first, the squirrel felt uncomfortable and tried to behave in a not-so-friendly manner with him. Usually, children used to harm small creatures with catapults, small toys made for shooting stones. When the squirrel found that the boy was not harming him, it became friend with the boy. The boy felt so happy, and he started bringing cakes and biscuits for the cute little squirrel. When the squirrel grew big and bold, it started searching for snacks by jumping into the boy’s pockets. The squirrel’s friends and relatives thought that the young squirrel was foolish for trusting a human.

squirrel-493790_1920.jpg
Squirrel
 
When the spring season began, the banyan tree started to produce small red figs. The tree branches were filled with different kinds of birds like the red-bottomed bulbul, parrots, myna, and crows. All these birds used to fight with each other on the branches. The sounds that all these birds made, turned the banyan tree into the noisiest place in the garden.
 
shutterstock_268134470.jpg
Birds on branches

The boy made a primitive platform on the tree branch to sit and relax in the afternoons. He took a cushion from his living room, and he was leaning against the tree. And so, he could read his favourite books on the tree when the afternoon was not too hot. He also made a tree library with his favourite books like 'Treasure Island', 'Huckleberry Finn', and 'The Story of Dr. Dolittle'.
 
shutterstock_657504721.jpg
Tree library

When the boy gets bored of reading, he could see down and look at the world below from the tree. The tree is so big and tall, and so the boy could see anything in a clear view. On one particular afternoon, the boy saw the classic fight between the mongoose and the cobra. He had the best possible view from his position on the tree, and it was the fight between two natives of the wild.
 
shutterstock_103496963.jpg
The boy could see anything in a clear view
  
Glossary from the paragraphs \(1\) - \(6\) of "The Banyan Tree":
 
No.
Words
Meanings
1.
MagnificentMarvellous, wonderful
2.
SpySecret agent/ Watch secretly
3.
TwistingTwiddle, turn
4.
CatapultA forked stick with an elastic band fastened to the two prongs, used by children for shooting small stones
5.
InvasionTo forcefully go to any place where we are not welcome
6.
ResentDislike; feel angry about
7.
MorselsSmall bits of food/ Small pieces of food
8.
DelvingGoing deep into/ Search for something
9.
SquabblingFighting over small things
10.
During the fig seasonThe time when figs appear
11.
CrudePrimitive, raw
12.
Propping myself upLeaning against/ To stop (something) from falling or slipping by placing something under or against it
13.
Grandstand view
A clear view from the best position (a grandstand is a large covered space with rows of seats for people to watch sports)
Reference:
National Council of Educational Research and Training (2007). The Banyan Tree (pp. 124-138). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.
 
*Banyan tree: By Kiran Gopi - Own work, CC BY-SA 2.5 in, https://commons.wikimedia.org/w/index.php?curid=15023516