Once it's left it rarely comes back. Another relationship is that of a ship that's sailed to sea or plane that taken off. You get the picture, especially if you've ever missed a train, plane or boat, it doesn't feel good. A key point is that timing matters in taking advantage of an opportunity.
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.