When someone quotes a great author, they are often not standing on a single sentence, but on the larger meaning of some story signified by that sentence. Star Trek's Tamarians whole language was references to stories -- "Darmok and Jalad at Tanagra" is, for them, a highly compressed statement. So literature enormously expands our vocabulary, allowing us to use quotes as "pointers" to ideas much larger than anything we could state briefly.

Humpty is a great story: http://sabian.org/looking_glass6.php, it's a wonderful exploration of meaning and usage.

But I'll unpack some of here.

Here's the lead up to the quote I gave:

"[Humpty said:] As I was saying, that seems to be done right — though I haven't time to look it over thoroughly just now — and that shows that there are three hundred and sixty-four days when you might get un-birthday presents —'

'Certainly,' said Alice.

'And only one for birthday presents, you know. There's glory for you!'

'I don't know what you mean by "glory",' Alice said.

Humpty Dumpty smiled contemptuously. 'Of course you don't — till I tell you. I meant "there's a nice knock-down argument for you!"' 'But "glory" doesn't mean "a nice knock-down argument",' Alice objected."

I think it is clear that Humpty's meaning was quite obvious, and Alice's complaint a bit dense. But while Humpty insists that he must tell Alice what he means, we can see that he needn't.

Of course, this word commanding business is as dangerous as you note, and Lewis Carroll is on the case:

"Alice was too much puzzled to say anything; so after a minute Humpty Dumpty began again. 'They've a temper, some of them — particularly verbs: they're the proudest — adjectives you can do anything with, but not verbs — however, I can manage the whole lot of them! Impenetrability! That's what I say!'

'Would you tell me please,' said Alice, 'what that means?'

'Now you talk like a reasonable child,' said Humpty Dumpty, looking very much pleased. 'I meant by "impenetrability" that we've had enough of that subject, and it would be just as well if you'd mention what you mean to do next, as I suppose you don't mean to stop here all the rest of your life.'

'That's a great deal to make one word mean,' Alice said in a thoughtful tone.

'When I make a word do a lot of work like that,' said Humpty Dumpty, 'I always pay it extra.'"

On the one hand, words can have many meanings, and any particular meaning must in part be taken from context. On the other hand, if we just try to _impose_ a meaning on a word, we defeat all communication, and make ourselves ridiculous to boot.