This is a single blank A4 photocopy that had been re-copied 100 times.
Copy-machines never create perfect photocopies, they always catches dirts and distort the original image. In repetition of re-copying, the dirts each time appeared on the photocopies were accumulated bit by bit and became the obscure gray spots increasing in succession.
In the end, the original image of blank A4 paper which was the white paper, had turned into the black paper.
The process of 100 times re-copying was documented as the list of the copy machine- manufacture numbers and presented next to the result titled Copy of white paper, contradictory unfolded its appearance as the Black paper.