There is no substitute for simply knowing these primary associations.

From E.D. Hirsch's Cultural Literacy.

There is no substitute for simply knowing these primary associations. They must be called up with lightning speed in the course of reading and conversing. We do not have the luxury of figuring out such associations one at a time. We may do this with one or two words in a paragraph - that is the way we learn new words - but we cannot pause over many words at a time. When we encounter U.S. Grant, the primary associations must be available to us in milliseconds: that he was an important Union general, that he became president, that he drank. These are some of the implicit associations needed to make meaningful what is explicitly written about Grant.

Research into the importance of primary associations thus introduces a subject of profound significance for teaching reading and writing. Successful communication depends upon shared associations. To participate in the literate national culture is to have acquired a sense of the information that is shared in that culture. No adult-level discourse retreats to the rudiments of knowledge. If assumptions about rudiments could not be made, ordinary discourse would be so lengthy and intricate as to obscure its own point.

Educators in the Rousseau-Dewey tradition, who favor less emphasis on mere fact and more emphasis on the intensive study of a few cases, encourage us to believe that students will thereby understand general principles and learn how to think critically. But literacy requires us to have both intensive knowledge of relationships and extensive knowledge of specifics. We need not only a general understanding of the principles of biology (which would enable us to infer that canaries breathe and lay eggs) but also specific knowledge of facts about canaries. We need to know not only the broad social and historical significance of the American Civil war but also who U.S. Grant was, and what the word Appomattox signifies. It is not enough to say that students can look these facts up. The research reviewed above shows that in order for readers to integrate phrases into comprehensible meanings, they must already possess specific, quickly available schemata. When readers constantly lack crucial information, dictionaries and encyclopedias become quite impractical tools. A consistent lack of necessary information can make the reading process so laborious and uncommunicative that it fails to convey meaning.