smell the barn

John GrishamのThe Racketeerも終わりに近づいて来ました。
I take a deep breath and feel like crying. This project has been on the drawing board for over two years, and during most of that time the odds of a successful outcome were at least a thousand to one. A series of loosely connected events had to fall perfectly into place. We’re not yet at the finish line, but we are in the homestretch. I can smell the barn.
慣用句らしい "smell the barn" は文脈からすると終わりが見えるの様な意味の様ですが、由来も知りたいので辞書で調べます。
・Wiktionary: To experience heightened anticipation or to act with renewed speed or energy as one approaches a destination, goal, or other desired outcome, like a livestock animal at day's end returning to its barn.
なるほど家畜なら家畜小屋は匂いで分かるのは納得。この表現を説明している他の辞書は見つかりませんでした。