This is what I try to communicate to people when teaching exegesis.
Intertexture is “a text’s representation of, reference to, and use of phenomena in the ‘world’ outside the text being interpreted. In other words, the interaction of the language in the text with ‘outside’ material and physical ‘objects,’ historical events, texts, customs, values, roles, institutions, and systems.” Intertexture is, in other words, those points of intersection within a text with other textual (oral or scribal), social, cultural, or historical worlds that are not the immediate world that is created by the text itself. Intertexture is the intersection of the inner world of the text, which is created by literary and narrative means, with the outer world within which the text developed. Intertextual analysis tries to determine the way the text configures and reconfigures phenomena from the world outside the text. There are four kinds of intertexture: oral-scribal, cultural, social, and historical. Oral-scribal intertexture pertains to oral or written sources, canonical and noncanonical, utilized by a discourse. It also involves how these sources were utilized, whether by recitation, recontextualization reconfiguration, narrative amplification, or thematic elaboration. Cultural intertexture is a text’s interaction with culture through direct reference or allusion and echo, to word and concept patterns, values and codes, and myths. Examination of this interaction with culture helps to determine the self-understanding and stance toward culture reflected in the text, whether affirming, challenging, or reconfiguring. It seeks to delineate how the text interacts with culture and positions itself toward it. (Duane F. Watson [ed.], The Intertexture of Apocalyptic Discourse in the New Testament 2-3)
This is precisely why one cannot blend biblical books together. The language that is used from one biblical book does not necessarily have the same referent in another. This is done all of the time. We are told that Daniel interprets Matthew and Matthew interprets Revelation. We are told that prophetic referents in the OT must have the same referent in the New when the referents are clearly different.