::::Since this is an encyclopedia, not literature or poetry, I also think "conceit" is a poor word choice here.  I don't see any analogy or extended metaphor in the motivation for the en passant rule.  The real problem is that the entire final paragraph of the section is uncited and not supported by the reference listed in the article, so it may be WP:OR original research.  I removed it.  If it is cited, it can be restored.