"The composition of religious imagery is not left to the initiative of the artist, but is formed upon principles laid down by the Catholic Church and by religious tradition... The execution alone belongs to the painter, the selection and arrangement of subject belongs to the Fathers."

The above quote is often cited as an "instruction" from the Second Council of Nicaea, but this passage is not found in the dogmatic canons issued by the Council. Where does it come from and what does it mean to the contemporary Christian artist?