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A very important metpahor actually comes in the third paragraph of this great satirical essay, when the speaker refers to the mother of an Irish child as a "dam." What is important about this descriptive detail is the way in which dam is a word normally used to indicate the mother but only of animals. Thus it is that this metaphor prepares us for the "modest proposal" of the speaker by implicitly comparing Irish children and their mothers to animals. Of course, if we consider the Irish to be little better than animals, than we will have no qualms about treating them like animals, to be reared and used for food to feed us. Thus this metaphor is a very important one to focus on in the way that it foreshadows what is to come in the rest of the treatise. Of course, throughout the entire essay, the real satire lies in the way that Swift is not representing his own views at all, but mimicing the views of his contemporaries, and taking them to their logical and terrifying conclusion.