it took half a century for the accumulated wisdom to be codified when in 1979 the second-tier screenwriter Syd Field published Screenplay: The Foundations of Screenwriting. His prescribed structure was this:

a 30-page opening act filled with character introduction, backstory exposition and the plot’s central conflict. This set-up ends with a development that dramatically raises the stakes of the storyline, introducing a conflict or ambiguity that challenges the audience’s assumptions of the story’s trajectory.

a tense 60-page second act filled with physical and/or emotional peril leaving the audience anxious about the protagonist(s)’s fate. Then, here too, an unexpected twist that adds an entirely new dimension and portends doom.

a 30-page resolution, in which previously glossed over characters and/or plot points are revealed to be crucial and previous audience assumptions are undone until, with five pages remaining, triumph for the protagonist and comeuppance for the villain.

If all that sounds pat and artless, it should not. Carte blanche is not freedom; it is the prison of infinite and unnecessary choice. As the 16th century French philosopher Michel de Montaigne wrote, it is boundaries that liberate and enhance, analogizing that breath “forced through the narrow passage of a trumpet, comes out more forcible and shrill.” Which is why we don’t bemoan the sameness of Shakespeare’s 154 sonnets, each 14 lines of 10 syllables in iambic pentameter, each an astonishing and unique snowflake.