It seemed to me as if nothing would or could ever be known. all that had so long engaged my attention suddenly grew despicable.
what change has the character experienced? he no longer enjoys his work.
he has gained a new appreciation for his work.
he has become closer with this friends.
he has taught something to his friends.

 He no longer enjoys his work.

In this excerpt, the speaker tells us that everything that he had previously been interested in suddenly became horrible to him. It is likely that the work the speaker was engaging in stopped being interesting or enjoyable for him. Moreover, he states that he began to feel as if nothing would or could ever be known. Therefore, it seems that the source of his frustration is that the speaker wanted to find out the truth of something, but now believes that it cannot be known.

in this passage from chapter 6 of "animal farm", by george orwell, what the author is ridiculing in this passage is the frivolity of some rules.

clover, the mare, believes she remembers that the fourth commandment forbade sleeping in beds because it was something that humans did. snowball, napoleon, and the pigs are brain-workers who look after the welfare of the farm. they are the obvious leaders because they are smart, and so they are entitled to eat the best food and sleep in beds. it is squealer, who says these lines making the difference between sleeping with sheets, what humans do, and sleeping in beds, what pigs do. the unwillingness to question authority makes the oppressed to obey without thinking.