How we cite our quotes:
Gradually, I became used to seeing the gentleman with the black whiskers. I liked him no better than at first, and had the same uneasy jealousy of him; but if I had any reason for it beyond a child's instinctive dislike, and a general idea that Peggotty and I could make much of my mother without any help, it certainly was not the reason that I might have found if I had been older. No such thing came into my mind, or near it. I could observe, in little pieces, as it were; but as to making a net of a number of these pieces, and catching anybody in it, that was, as yet, beyond me. (2.63)
This passage sums up in a nutshell the difference between main-character-David and narrator-David. Main-character-David is still a child, with a child's instincts. He knows that something is wrong with Mr. Murdstone, but he doesn't know what. But narrator-David knows all too well what Mr. Murdstone will mean for character-David. And narrator-David's pity for his past self, who "could observe, in little pieces" but could not "[catch] anybody," influences our own sympathy for character-David.
There was more laughter at this, and Mr. Quinion said he would ring the bell for some sherry in which to drink to Brooks. This he did; and when the wine came, he made me have a little, with a biscuit, and, before I drank it, stand up and say, 'Confusion to Brooks of Sheffield!' The toast was received with great applause, and such hearty laughter that it made me laugh too; at which they laughed the more. In short, we quite enjoyed ourselves. (2.82)
Mr. Murdstone brings David on a visit to Lowestoft, which is near Blunderstone, David's home town. This is when he is still courting Mrs. Copperfield, before Mr. Murdstone has sealed the deal. So, he doesn't want to mess things up by alienating David yet. On this visit to Lowestoft, Mr. Murdstone meets up with two friends of his. And he warns them not to talk too openly of Mrs. Copperfield because "Brooks of Sheffield" – a.k.a. David – is listening. David is so innocent and naive that he does not realize who Brooks of Sheffield is, and he doesn't know that they are laughing at David by making him drink a toast to his own confusion. This scene is an excellent illustration of one of the common lessons of this novel: to be innocent is to be easily deceived. Emily would be another great example of this cynical lesson.
God help me, I might have been improved for my whole life, I might have been made another creature perhaps, for life, by a kind word at that season. A word of encouragement and explanation, of pity for my childish ignorance, of welcome home, of reassurance to me that it was home, might have made me dutiful to him in my heart henceforth, instead of in my hypocritical outside, and might have made me respect instead of hate him. (4.31)
When David returns to his home made strange by his mother's marriage to Mr. Murdstone, the narrator goes into this long speculation about his entire life might have been different and better if Mr. Murdstone had offered him one word of encouragement at this key moment. This seems to be the key tragedy of this novel: there are a thousand moments when a single word can make all the difference in improving (or ruining) that kid's life. But you can only know in retrospect, looking back on the event, what would have made things better.