It is pointed out that, after Gutenberg's introduction of movable type an the printing press in the fifteenth century, and due to the influence of the Renaissance, Western culture entered a period of visual efflorescence. Then, due mainly to the influence of the Scientific Revolution, there occurred a derogation of visual experience in favour of word and abstract number. It is argued that, in the late twentieth century, technology, supported by developments in scientific theory, has given new efficacy to visual thinking and experience. Increasingly, illustrations of various types are employed to give meaning to otherwise incomprehensible data. Today's technical communicator must learn to deal effectively with the new demands of a visual culture, becoming not only a master of the new technology but also a possessor of a deep understanding of the theories and structures of visual knowledge.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>