Few things delight a politician more than being able to cite external support for their arguments.
In that respect, they resemble publishers or theatre producers who quote happily, if sometimes selectively, from reviews of their oeuvres.
You know the sort of thing. "This play is both interesting and new", the billboard will shriek, neglecting to add the rest of the quote: "Sadly, the new bits are not interesting and the interesting bits are not new."
Today at Holyrood Alex Salmond turned to the Sage of the Scotsman to spice up his replies.
The Sage? Bill Jamieson, of course.
The worthy Bill takes a full page in the Scotsperson to diagnose the SNP's electoral problems - but to suggest that they have a counter-weight; to wit, the calibre of their Labour opponents.
In particular, Mr Salmond quoted at length - and with obvious approval - the suggestion by Mr Jamieson that Labour's Iain Gray has soporific tendencies.
No doubt pressed for time, Mr Salmond found himself unable to feature the conclusion of the article in which the bold Bill also questioned the intrinsic purpose of the SNP leader.
Still, the quotation, triumphantly delivered, enabled the first minister to land a hit, a very palpable hit, upon the Labour leader.
The exchanges had focused upon the economy and public spending.
Mr Gray suggested that the SNP leader had failed in his government's declared purpose, to grow the economy.
Labour's essential purpose is to plant in the public mind the concept of a "Salmond slump".
That, one supposes, would be in addition to the financial crisis and recession of the past few years.
Again, presumably, it was lack of time which prevented Mr Gray from reminding MSPs which party held sway at the Treasury while those catastrophic events occurred.
Ah, the liberation of opposition. No longer does Iain Gray have to defend UK economic policies.
He can lambast both the Scottish and UK governments simultaneously.
To be fair, Mr Gray's core point was that there were cuts in progress now, in nursing and teaching posts, which would impact upon Scotland's economic prospects.
Again, though, the snag for the Labour leader is that Mr Salmond has a ready answer. Two, in fact.
He can lambast the UK governments, past and present, for the overall handling of the economy which, he says, has brought about the cuts in spending.
Plus he can - and did - argue that his government can only make a significant impact upon the post-recession economy by gaining and deploying the full range of fiscal and financial levers currently reserved to Westminster.
As to the others, Tavish Scott pursued the problems with the Commonwealth Games at Delhi.
Both Mr Salmond and, earlier, the Sports Minister Shona Robison were notably emollient, no doubt partly with an eye to preventing any backlash which might damage the Glasgow games in 2014.
And there were intriguing exchanges between the first minister and Annabel Goldie. These confirmed that the Scottish Government is preparing options with regard to the longer-term funding of universities.
Mr Salmond was firm: no to up-front tuition fees. I believe he has also set his face against reviving the graduate endowment.
After all, the abolition of that levy will feature substantially in the SNP's list of claimed gains from their tenure in office.
Instead, a forthcoming Green Paper may feature around five options, including possibly a graduate tax and other "innovative" plans.
Scotland awaits with interest.