Theory:

     The half-hour was up. “I think I’ve annoyed you enough,” I said, grinning. “Thank you for...”
 
     “Stay.” I waited. “Have some tea. I can show you the garden.”
 
     The garden was as big as a park, but Stephen Hawking covered every inch, rumbling along in his motorised wheelchair while I dodged to keep out of the way. We couldn’t talk very much; the sun made him silent, the letters on his screen disappearing in the glare.
 
     An hour later, we were ready to leave. I didn’t know what to do. I could not kiss him or cry. I touched his shoulder and wheeled out into the summer evening. I looked back; and I knew he was waving, though he wasn’t. Watching him, an embodiment of my bravest self, the one I was moving towards, the one I had believed in for so many years, alone, I knew that my journey was over. For now.
Explanation:
 
When we talk to people who have a lot of intellect, we tend not to keep track of time. We look forward to gain insights from the person we look up to as an inspiration. Kanga notices that the half an hour that was scheduled was already up. He reluctantly decides to end the meeting. At the same time, he is also grateful for the time he spent talking to Hawking. He notes that he has annoyed Hawking enough, as this is a reference to the sarcastic note made earlier in the lesson. When he is about to end the meeting with a formal thank you and talk about how enlightening the session had been, he is cut short by Hawking.
 
Hawking very surprisingly does not want to end the meeting. At the same time, he does not want it to be interactive either. He just asks for the company and to have tea with him. This probably indicates that Hawking liked the conversation with Kanga. He might be feeling the same way as Kanga did, that he could connect with a disabled person as they both are experiencing the same kind of situation. Hawking offers to show Kanga the garden. Generally, all interviews are just a random conversations between people and are very formal. But when one establishes a deep connection with a person, he tends to reveal his personal side and things that he enjoys the most. Hawking takes Kanga to the garden and shows him around every nook and corner. The garden was as big as a park. Hawking moves around in his motorised wheelchair, followed by Kanga, who makes sure not to dodge or come in his way. It was a very silent scenario and they dwelled in it. It was not an awkward pause as Hawking enjoyed every moment, basking in the sun making his letters on screen also pause for a while.
 
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Gazing at the sun in the park
 
What was scheduled for half an hour went on for another extra hour. Kanga did not know what to do or how to react. He knew that he could not kiss or cry as a part of the farewell. But he just touches Hawking's shoulders which is enough to express all his emotions and love, and wheels out of the garden. It was a summer evening and when Kanga looked back, he knew that Hawking was inwardly waving although he was paralysed. Watching Hawking was an embodiment of himself for Kanga, as this was what he strived to achieve in a few years from now. He says that this one beautiful chapter is over for now, and there is a lot more for him to strive for.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1
ReluctantUnwilling to do something
2
GrinningSmiling widely
3
RumblingTo travel with a sound
4
GlareShine brightly
5
EmbodimentThe visible form of an idea
Reference:
National Council of Educational Research and Training (2008). Honeydew. A Visit to Cambridge - Firdaus Kanga (pp. 96-104). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.