New Criticism is a school of literary analysis stressing that a text's meaning is found within the text itself, rather than by studying the author's life or other texts. It was popularized by the 1941 publication of "The New Criticism," by John Crowe Ransom, and, as a movement, extended roughly from the 1930's to the 1960's. In modern times, New Criticism's influence has dwindled into the close reading that it embodies.
New Criticism assumes that a text has an existence all its own, and, as T.S Eliot says, is seperate from its author much as a chemical reaction is to its catalyst. One causes, but is not affected by the other. A good literary critic is then one who examines a text thoroughly and finds symbols, patterns, tensions, and other sources of meaning, whereas a bad critic calls into play outside influences, such as an author's bibliography.
Bressler, Charles E. Literary Criticism an introduction to theory and practice
. New Jersey: Pearson Education, 1994.