Indentation of the first paragraph in a section
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  [...] in Robert Bringhurst's Elements of Typographic Style, he states that
  "opening paragraphs" should be "flush left" because "[t]he function of
  a paragraph indent is to mark a pause, setting the paragraph apart
  from what precedes it. If a paragraph is preceded by a title or
  subhead, the indent is superfluous and can therefore be omitted".