The third book of short works for young pianists by Johann Sebastian Bach (after ''Easy Pieces'' and ''Short Pieces'') contains ''Little Preludes'' which, for over a century and a half, have formed part of the basic repertory of piano studies all over the world. The principle of gradation has been strictly applied in the selection and arrangement of the works. In order to characterise the lasting value of Bach's ''little preludes'', let us quote Albert Schweitzer, one of the greatest experts on the master's art: ''It is just in these short pieces that Bach's unusual greatness is manifested. He had wanted to write short exercises and wrote compositions, whose contents and mood must be graven on the memory of everyone, who once become familiar with them returns to them as an adult with ever new delight''.