Husn al-taʿlil (beautiful causation) assigns a pleasing, imaginative, but nonfactual cause to a state or event. The proposed cause is an artistic explanation, not a scientific or historical account.
The device connects an observed feature with a fitting fictional reason. If the stated cause is simply the real cause, the sentence is ordinary explanation rather than husn al-taʿlil. If the invented cause does not suit the context, the rhetorical charm is weak.