This book is to commemorate the 50th anniversary of Tlatelolco massacre held in Mexico City October 2nd 1968. The box contains 50 separate papers with the date october 2nd of each year written in every card from 1968 to 2018 each. 1969 card is completely red and as the years go by, the red starts to turn into black. If you display the 50 cards all together you can see how the colors gradient changes in a diagonal way from top left to bottom right. Blood becomes mourning in a scale of color.