Tell me how I'm supposed to breathe with no Eyre?

How would you best describe the central idea of this chapter? Which phrase from the chapter best helps develop the central idea? 

This is a chapter centered around hardship, standards, and isolation.  At the start of the chapter, Jane describes the hardships of the life she is living, and how those hardships are especially relevant in the winter.  Walking miles to church, insufficient clothing for the conditions, and an inadequate food supply were all hardships that Jane and the other girls had to deal with in the winter.  

After giving insight into what her life was like at the time by describing such hardships, the chapter shifts the scene in a classroom where Mr. Brocklehurst arrives.  Mr. Brocklehurst is first presented by Jane as a stern and well-known character whose purpose is to represent authority in some way.  Mr. Brocklehurst begins to talk to one of the teachers, Miss Temple, and then goes on to explain to her his dissatisfaction with the way his standards are being implemented in the classroom.  He believes that the girls are given too much clothing of too high quality and that they are being fed too much.  He is even unhappy with the hair styles of the girls, not wanting to see any braids or curls (even if they are natural).  

Mr. Brocklehurst's commentary on the girl's hair styles is interrupted when Jane, who had tried to remain unseen by Mr. Brocklehurst, loudly drops her slate.  Jane had tried to remain unseen due to the fact Mr. Brocklehurst knows about her past, including the fact that she is a former orphan.  When Jane, drops her slate, Mr. Brocklehurst realizes her presence and precedes to isolate her from the rest of the class.  He isolates her by having her put on top of a stool and explains to the whole class as to why Jane is a liar.  As Mr. Brocklehurst leaves, he states, "Let her stand half-an-hour longer on that stool, and let no one speak to her during the remainder of the day."  Jane is mortified.  

It is hard to pick out one phrase that best helps develop the central idea of a chapter based around hardship, standards, and isolation.  However, I feel that the quote "I was in no condition to note particulars" most accurately helps develop the central idea.  This quote comes from when Jane is hoisted up onto the stool to be at eye level with Mr. Brocklehurst.  By stating that she was "in no condition to note particulars," Jane is alluding to the fact that her bizarre, current circumstances, which include hardship, unjustifiable standards, and isolation, have created a situation in which her mind is unable to focus on details.