Martin Gardner's Mathematical Games columns in Scientific American inspired and entertained several generations of mathematicians and scientists. Gardner in his crystal-clear prose illuminated corners of mathematics, especially recreational mathematics, that most people had no idea existed. His playful spirit and inquisitive nature invite the reader into an exploration of beautiful mathematical ideas along with him. These columns were both a revelation and a gift when he wrote them; no one--before Gardner--had written about mathematics like this. They continue to be a marvel. This volume is a collection of Irving Joshua Matrix columns published in the magazine from 1960-1980. There were several collections of Dr. Matrix, the first in 1967; they were revised as Gardner reconnected with the good doctor over the years. This is the 1985 Prometheus Books edition and contains all the Dr. Matrix columns from the magazine.