Thus the debate. Thus the choice.

The Latin, I suppose, is the clue. It indicates that we are dealing not with a cunning politician nor with the wicked media but with one of Her Majesty's civil servants.

Thus, Colin McKay, a senior Scottish government civil servant, is quoted as noting: "We cannot assert as a priori fact that we can achieve a currency union with the UK but we can set out why we think it is the best option."

Cue an onslaught from the opponents of said SG to the effect that Mr McKay's comments scarcely square with the certainty emanating from the first minister.

In practice, of course, the remarks attributed to Mr McKay amount to a statement of the blindingly obvious.

A priori, in advance, one cannot state with absolute certainty that a currency union could be established and sustained between an independent Scotland and the rest of the UK.

Regular readers of this site, indeed, will have had this point drawn to their attention frequently. Nevertheless, it is a topic of substance in terms of political debate, in terms of tone.

It is in the interests of the opponents of independence - such as the Chancellor of the Exchequer - to draw attention to potential problems and to state that such a deal is unlikely.

Those same opponents also point out that an alternative scenario - that of Scotland using the pound unilaterally - involves considerable potential problems.

They argue that an independent Scotland, in such circumstances, would have no say in the Bank of England's interest rates, no lender of last resort in case of a financial crisis, and no central bank backing mortgages, savings and pensions.

Which, of course, is why Scottish Ministers advocate a cross-border agreement. It is in the interests of the SNP - who favour a common currency - to state that such a sterling zone could be established to the advantage of both Scotland and rUK.

'No certainty'

If Alex Salmond were to turn to the language of ancient Rome, he might say that such a currency union would make sense, a posteriori.

That, in the event of a Yes vote in the referendum, it would be in the interests of rUK to maintain a stable arrangement with the newly reformed state to the north.

He might say that if there is a general desire for economic stability then, a fortiori, there would be a case for an agreement on sterling, once independence was an endorsed prospect, a pending reality.

The response from Mr Salmond's opponents will be that there can be no certainty that such a sterling zone would be viewed as suiting rUK.

That, consequently, there can be no certainty in the Scottish government's offer.

Thus the debate. Thus the choice.