Theory:

     When I returned home from the outset of my second voyage to England, my brother Jyotirindra and sister-in-law were living in a river-side villa at Chandernagore, and there I went to stay with them.
 
     The Ganges again! Again those ineffable days and nights, languid with joy, sad with longing, attuned to the plaintive babbling of the river along the cool shade of its wooded banks. This Bengal sky-full of light, this south breeze, this flow of the river, this right royal laziness, this broad leisure stretching from horizon to horizon and from green earth to blue sky, all these were to me as food and drink to the hungry and thirsty. Here it felt indeed like home, and in these I recognised the ministrations of a Mother.
 
     That was not so very long ago, and yet time has wrought many changes. Our little riverside nests, clustering under their surrounding greenery, have been replaced by mills which now, dragon-like, everywhere rear their hissing heads, belching forth black smoke. In the midday glare of modern life even our hours of mental siesta have been narrowed down to the lowest limit, and hydra-headed unrest has invaded every department of life. Maybe, this is for the better, but I, for one, cannot account it wholly to the good.
Explanation:
  
The author of the story is Rabindranath Tagore. He had returned to India after his second trip to England. He went to a small river-side village known as Chandernagore in West Bengal, where his brother Jyotirindra and his wife stayed. He went to spend some days with them.
 
Chandernagre.jpg
*Chandernagore - a beautiful green village in West Bengal!
  
He loved the Ganges river that flowed in the area. He was reminded of his days and nights that he spent in the place, which was so extraordinary that he could not describe with words. Those days were relaxed and happy, yet sad with an intense desire. He was used to hearing the sad, continuous murmuring of the river water while he enjoyed the cool shade of the banks filled with trees. The fully lit up Bengal sky, the southern breeze, the flowing of the river, the comfortable laziness, a lot of free time to spend, doing all activities from the ground to the sky (the line at which the earth's surface and the sky appear to meet) - all these were so important to him, like food to a hungry man and water to a thirsty man. He felt this nature was his home, and he was able to feel the care and assistance of a Mother.
 
riverside.jpg
The plaintive babbling of the river made him feel at home!
 
It had not been many years ago, but still, many changes had happened. The small nests (can also refer to houses, along the banks) in the river-side trees surrounded by the lush greenery, had been changed. Mills had come up in those places, like a huge dragon, with heads (maybe the chimneys from the mills) that made sharp noises and emitted black smoke.
 
dragon.jpg
The mills seemed like dragons to him!
  
The hours of midday sleep (nap) had been reduced due to modern life struggles, and the multi-faceted problems, which leads to disturbances in every part of our life. There can be some good in the modern technological advancements, the author says, but he cannot agree that it is completely for good - there are ill effects of modernisation also.
 
Meanings of difficult words:
  
No.
Words
Meanings
1
ineffabletoo great to be expressed or described in words
2
languidrelaxed, lazy
3
longinga yearning desire
4
horizonthe line at which the earth's surface and the sky appear to meet
5
ministrationsthe provision of assistance or care
6
wroughtmade in a specified way
7
belching(especially of a chimney) send out large amounts of (smoke or flames)
8
siestaan afternoon rest or nap
9
hydra-headedhaving many facets or aspects
10
unresta state of dissatisfaction, disturbance, and agitation
11
voyagea long journey involving travel by sea or in space
12
babblingthe continuous murmuring sound of flowing water
Reference:
*Chandernagore Image courtesy - https://commons.wikimedia.org/wiki/File:Chandernagre_Govt._College.jpg
  
State Council of Educational Research and Training (2019). Term-2 English Standard-8. My Reminiscence - Rabindranath Tagore(pp. 113-126). Published by the Tamil Nadu Textbook and Educational Services Corporation.