For things that clearly do have the springlike quality of shifting irreversibly if pulled (or pushed) too far, like the collapse of ice sheets or the melting of permafrost, a boundary system that seeks to stop you getting too close to the threshold seems as sensible as a safety rail is on a parapet.

ECONOMIST: The global environment

The additional-member voting system proposed by Lord Jenkins requires boundary changes that could not in any case be introduced in time for the next general election.

ECONOMIST: Long grass, tough choices

Dr. THOMMES: Well, what we think happened in our solar system is that we are an example of a system that was sort of near the boundary between something that actually formed gas giants, formed, well, the Jupiter and Saturn that we see today, and something that if conditions had been a little bit different wouldn't have really formed any gas giants at all.

NPR: What Makes Our Solar System Special?

The peer also said it would ensure that the boundary review was based on the new system of individual voter registration, to be brought in under the bill with all-party backing.

BBC: Peers vote to block MP constituency boundary changes

Given that, SNP ministers say, rUK ministers and the financial system would rationally prefer a stable sterling zone rather than Scotland deploying sterling free from constraint on their northern boundary.

BBC: Scottish independence: Political battle over currency