In teaching Mikrokosmos to some four score children over a period of several years, I have realized that it serves numerous musical purposes beyond just that of being another series of pieces and studies for pupils. In addition to laying a strong and richly varied foundation for the understanding and performance of twentieth-century music, it presents almost unending varieties of situations for facilitating sight-reading and transposition. The work offers virtually every pianistic and musical problem to the student, and interestingly enough, its use gives him increased insight into music of the past as well as of the present.