John William Waterhouse, The Missal (1902)

This is of course the counterpart (its "sister" painting, if you like) of Waterhouse's other painting, The Crystal Ball.

Ecclesia

The above icon shows an... unusual representation of the Crucifixion.

The woman riding on the beast is of course Ecclesia. The beast itself of course symbolizes the Gospels. And the figures on the other side of the Cross are of course Our Lady and St John.

The reason why the latter two are both on the same side though is curious. More normally they would be on either side of the Cross, and the figure balancing out Ecclesia would be Synagoga.

In England the two of them - Ecclesia on one side of the Cross and Synagoga on the other - can apparently still be seen - albeit mutilated - in the Cathedrals of Rochester, Lincoln, Salisbury, and Winchester.