In Sargent's 1916 manual, why must every action in a photoplay have a motive the audience can see, and how does he tell an explained or self-motived action from an unmotived one?

Sargent (Technique of the Photoplay, 3rd ed. 1916, ch. X 'Motives') says a character always has a reason, but an audience cannot see it unless the film shows it, so an act that is neither obvious nor explained 'is absurd'. He asks for motives that an audience will accept as 'reasonable and logical', and he gives 'motivation' a second job: every important action must show a definite bearing on the plot and advance it toward the climax. His examples (green-cow drunk, fence beside an open gate, suitor ejected as a drug fiend, plot-needed fire) illustrate these claims; they are not tests. This is one trade editor's 1916 rule set for silent one- and two-reelers, with no measured effect. Curator qualifications: All ten ch. X excerpts sit exactly at the stated offsets. The claim/example split holds, and so does the synthesis that 'motiving'/'motivation' is used loosely after para 1. Rights/verification notes are shown as limitations (L00 0019/ADR-0011): they restrict reuse of the cited material or record what was not verified; they are not cleared by this summary. Limitations: [component_reuse_restriction] Internet Archive OCR text; licence of the scan not re-read here (public-domain 1916 text per prior S10 review). Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://archive.org/stream/techniqueofphoto00sarg/techniqueofphoto00sarg_djvu.txt",
      "note": "sar.flat chars 96660-104324 (ch. X paras 1-12)"
    }
  ]
}