This work by Escher is a fitting illustration of Liberation Day, the day on which the Dutch celebrate the end of the German occupation in 1945. His birds and fish are wresting themselves free from the firm grip the tessellation is holding them in.
Escher created Sky and Water II in the freezing month of December 1938, in stark contrast to the beautiful weather we have in the Netherlands today. Six months earlier he produced a woodcut with the same subject: Sky and Water I. In it, all the birds and fish are moving to the right, whereas in II we see them moving in both directions. Viewed from above, the first black bird is flying to the right; the second one is flying to the left. Their fish counterparts at the bottom are engaged in the same movement. In the next row two birds are flying to the right and two are flying to the left. As do the fish in the corresponding row. Then there is a row with three birds heading right and left and three fish heading right and left. In the last row of each half there are four of them.
The fact that the upper half progresses into the bottom one and vice versa gives rise to a tessellation in which birds become residual shapes to the fish and vice versa. Looking up from the middle, the white shapes open themselves up and gradually lose their fish-shaped silhouettes; they merge and change into a white sky background in which the birds are flying. The opposite happens when you look downwards, starting from the centre. Due to this alternation of shape and residual shape it is hard to determine how many birds and fish this woodcut contains. Does a residual shape of a bird count as a bird? And if so, at what point does this stop? When described in writing, all this seems more complicated than the viewing of the print does, but the viewing of the print is no less complicated. Escher deceives the viewer’s eye, time and time again.