"Well, it's no use your talking about waking him," said Tweedledum, "when you're only one of the things in his dream. You know very well you're not real."
A loaf of bread, the Walrus said, Is what we chiefly need: Pepper and vinegar besides Are very good indeed-- Now if you're ready, Oysters, dear, We can begin to feed!
If you set to work to believe everything, you will tire out the believing-muscles of your mind, and then you'll be so weak you won't be able to believe the simplest true things.
Well, "slithy" means "lithe and slimy." "Lithe" is the same as "active." You see it's like a portmanteau - there are two meanings packed up into one word.