Theory:

     I remember well my shy remarks, one day, while stretching out to him my youthful foot. “Isn’t it awfully hard to do, Mr Gessler?” And his answer, given with a sudden smile from out of the redness of his beard: “Id is an ardt!’’
 
     It was not possible to go to him very often— his boots lasted terribly, having something beyond the temporary, some essence of boot stitched into them.
 
     One went in, not as into most shops, but restfully, as one enters a church, and sitting on the single wooden chair, waited. A guttural sound, and the tip-tap of his slippers beating the narrow wooden stairs and he would stand before one without coat, a little bent, in leather apron, with sleeves turned back, blinking — as if awakened from some dream of boots.
Explanation:
 
The author recounts an incident from his youth in which he asked Gessler about the challenges he encountered in his career. And, the bootmaker replied to him with a smile: It is an art!'. Mr. Gessler looked at his work as an artistic creation. Also, one could observe a change in the Gessler brothers' accents throughout the lesson (pronouncing p, t, k as b, d, g). It was due to influence from their mother tongue (German).

Since the boots purchased from Gessler's shop lasted for a long time, there wasn't any need for the author to visit Gessler's shop often. The author complements the bootmaker's work, stating, 'because the bootmaker's boots were created with great effort and prepared with good quality leather, they lasted for a longer amount of time.' The author emphasises the bootmaker's intellect here. He claims that the bootmaker knows how to produce high-quality boots.

Also, according to the author, the ambience of the shop was unique, unlike other shops. He always felt the peaceful atmosphere after stepping inside Gessler's shop. So, he compares Gessler's shop to that of the church as he thought it provided peace to a person while waiting at the wooden chair inside the shop.
 
The author also says one could hear the guttural sound and tip-tap of the bootmaker shoes that tapped the stairs as he descends the stairs to attend a customer entering the Gessler's shop. In addition, the author has provided a brief description of the bootmaker's appearance. The author says that the bootmaker would be dressed in a leather apron, with his shirt-sleeves turned back and slightly bent towards the buyer. Since he was always immersed in his job, he'd blink as if he'd just awoken from a dream about boots whenever a customer entered his shop.
 
Mr. Gessler.jpg
Mr. Gessler

The author here emphasises the bootmaker's dedication and commitment to his profession. As previously said, the bootmaker regards boot design as an art rather than a job.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Awfully Terribly
2.
Guttural soundA deep sound produced from the throat
3.
Ambience The atmosphere of a place
4.
EssenceThe most important feature or quality of something
5.
Dedication The hard work and efficiency that someone puts into an activity or a work
6.
Unique Being the only one of its type
7.
ApronA piece of cloth worn over the front of the body
8.
RemarksAn opinion or judgement
Reference:
National Council of Educational Research and Training (2007). Honeycomb. Quality - John Galsworthy (pp. 71-78). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.