One day when I was studying with Schoenberg, he pointed out the eraser on his pencil and said, “This end is more important than the other.” After twenty years I learned to write directly in ink. Recently, when David Tudor returned from Europe, he brought me a German pencil of modern make. It can carry any size of lead. Pressure on a shaft at the end of the holder frees the lead so that it can be retracted or extended or removed and another put in its place. A sharpener comes with the pencil. The sharpener offers not one but several possibilities. That is, one may choose the kind of point he wishes. There is no eraser.

John Cage