In this sense, we should continually be striving to transform every art into a science: in the process, we advance the art. Computer Programming as an Art (1974)
Science is what we understand well enough to explain to a computer. Art is everything else we do. Foreword to the book A=B (1996)
Science is knowledge which we understand so well that we can teach it to a computer; and if we don't fully understand something, it is an art to deal with it. Computer Programming as an Art (1974)