Theory:

     "I seem to myself like a child," he observed, "playing on the sea-shore, and picking up here and there a curious shell or a pretty pebble, while the boundless ocean of Truth lies undiscovered before me."

     At last, in 1727, when he was 85 years old, Sir Isaac Newton died,—or rather he ceased to live on earth. We may be permitted to believe that he is still searching out the infinite wisdom and goodness of the Creator, as earnestly, and with even more success, than while his spirit animated a mortal body. He has left a fame behind him, which will be as endurable as if his name were written in letters of light, formed by the stars upon the midnight sky.

     "I love to hear about mechanical contrivances—such as the water-clock and the little windmill," remarked George. "I suppose if Sir Isaac Newton had only thought of it, he might have found out the steam-engine, and railroads, and all the other famous inventions that have come into use since his day."

     "Very possibly he might," replied Mr. Temple; "and, no doubt, a great many people would think it more useful to manufacture steam-engines, than to search out the system of the universe. Other great astronomers, besides Newton, have been endowed with mechanical genius. There was David Rittenhouse, an American,—he made a perfect little water-mill, when he was only seven or eight years old. But this sort of ingenuity is but a mere trifle in comparison with the other talents of such men."
Explanation:
 
Isaac once told that he seemed like a child to himself. He said he was like a child playing on the sea-shores with shells and stones, while there was so much to discover about the endless sea in front of him.
 
child sea.jpg
"While the boundless ocean of truth lies undiscovered before me!"
 
Sir Isaac Newton died when he was aged \(85\), in the year \(1727\). The writer says he stopped himself from living on this earth. The writer says that he believed that Isaac Newton is still living somewhere searching for endless knowledge and the Creator (God) of the universe. He says Newton is sincerely looking for knowledge in his spirit form, with more success than when he was living in a body form. He has left behind huge fame for himself as if his name is written in a light, formed by the stars in the dark midnight sky.
 
Two characters, Mr. George and Mr. Temple, are in a discussion about Isaac. George said that he loved to hear about the clever mechanical devices that are made for specific purposes - like the small windmill and the water-clock. He further added that if Sir Newton had thought of steam-engines and railroads, he would have found those and other famous inventions also.
 
Mr. Temple agreed to Mr. George. He said many great people would have thought it was more useful to invent the steam-engines and railroads than to find about the universe, millions of miles away from us - as they are used in our day-to-day lives. There have been many great astronomers like Newton, who have been provided with great mechanical knowledge. For example, there was an American named Mr. David Rittenhouse, who made a small watermill when he was just seven or eight years old. But these type of inventions is very small, compared to their talents.
 
Meanings of difficult words:
 
No.
Words
Meanings
1
earnestlywith sincere and intense conviction
2
endurableable to be endured; bearable
3
contrivancea clever device or object that has been invented for a particular purpose
4
ceasedstopped
5
trifle
a thing of little value or importance
Reference:
State Council of Educational Research and Training (2019). Term-2 English Standard-8. Sir Isaac Newton- The Ingenious Scientist (pp. 84-97). Published by the Tamil Nadu Textbook and Educational Services Corporation