Symbolic proportion is the deliberate emphasis of objects in a work of art based on its importance as a symbol. This can sometimes also mean that in an artwork where symbolic proportion is applied, religious figures tend to be "bigger" or more emphasized compared to any other element a person may see in the piece.
The artist may have used symbolic proportion to emphasize the importance or prominence of Mary and Jesus Christ - this may be relative to any smaller objects around them in the scene.
The thesis statement is a statement of position
