Nor should we always go by the way a sentence looks.
"Blackbirds are black birds" appears to be analytic but is not; it is not a defining characteristic of the class of birds we call blackbirds that they must be black: an albino blackbird would still be a blackbird. Most of the members of the species are black, hence the name "blackbird," but this should not lead us into assuming that the characteristic that gives the species its name is always a defining characteristic. Again, "Business is business" looks like a simple "A is A"; but, as used on most occasions, its meaning is something like "In business, anything goes" and the proposition expressed by that sentence is not at all analytic. On the other hand, "If you study this chapter long enough, you'll understand it" doesn't appear to be analytic at all, but let us look again: How long is long enough? Suppose you read the chapter 50 times and still don't understand it, and someone says to you, "That only shows that you haven't read it long enough." We now begin to suspect that he is using "long enough" to mean "till you understand it." And if this is its meaning, it is analytic: "If you read it till you understand it, you'll understand it." (If, after you read it 50 times, he said, "I guess I was wrong you've read it long enough and you still don't understand it," then he would not be using the sentence to express an analytic proposition.)