Only yesterday did I come across ex-voto paintings for the first time, and I find myself haunted by them. An ex-voto painting is one dedicated to God or a saint in thanks for a favor received, usually in answer to a prayer. The painting usually depicts the situation needing help, and the supernatural power who secured it, and has an inscription at the bottom explaining what has happened.
Mexican artists Frida Kahlo and Diego Rivera were both very interested in ex-voto paintings as they are an important form of folk art in Mexico. Here is one such painting that apparently belonged to Kahlo.