In Exodus 11:5, 'the servant-girl behind the mill' [signifies] the most external affection for knowledge, since 'behind the mill' means that which occupies the very last place. The expression 'behind the mill' is used because 'the mill' has reference to matters of faith. For by means of a mill, grain is ground into flour and so prepared for making bread, and 'flour' means truth which results in good, 'bread' the actual good that results from it. Thus 'sitting at the mill' is acquiring and learning the kinds of things that will be of service to faith, and through faith of service to charity. This is why when the ancients described learning the basic elements of faith they described it as 'sitting at the mill', or learning elements even more basic as 'sitting behind the mill'. (Arcana Coelestia 7780)