A discussion of the distinction between a scientific discipline and a professional activity and of the reasons why "information technology" is a professional and not a scientific activity. The application of computers to the improvement of information handling is discussed as a professional advance similar to advances in medicine made possible by new instruments. A major new instrument, like the computer in information technology or the X-ray machine in medicine, may sometimes drastically change the practice of a profession. Some of the implications of the computer for librarianship are discussed in these terms.