Texts resonate within their cultural sphere; a fairly obvious point in and of itself, but one with greater implications. Textual resonance is the source of allusion, and to a more removed degree, symbolism and metaphor. The interesting part comes when you study different types of resonance.
Let's take, for examples, two comedic shows: Robot Chicken and Arrested Development. Both shows (which I am including, in a rather loose sense, as texts) resonate within their cultural spheres, and to a degree, are defined by the various norms and expectations within the confines of which they are created (if only so that comedic convention may defy them). Both shows are also utterly hilarious. However, the resemblence stops there.
Robot Chicken is externally resonant. It is a sponge, which soaks up external references, and creates amusing parodic twists. Its humor -to use a metaphor I am very fond of- hyperlinks out to other texts. In other words, if you don't get the reference, you won't get the joke. How do you get the reference? Expose yourself to the media and texts which are not defined within the show, except as parody.
Arrested Development chooses the opposite tactic. It sets up a web of internal references, and so becomes its own microcosm of culture. In other words, a human being understanding only the vaguest conventions of Western civilization would eventually find A.D. amusing, as they accustomed themselves to the internally resonant references.