Nothing is certain other than death and taxes, it is said.
If Scotland votes for independence the Scottish Government might not be responsible for death but it will certainly be in charge of taxes.
Tax, and the argument over it, goes to the heart of the independence debate.
Which is why First Minister Alex Salmond set up a Fiscal Commission made up of distinguished academics to look at this thorny issue.
Today they have issued two substantial reports. One is on the principles of a modern and efficient tax system in an independent Scotland. The other on what fiscal rules might govern that independent Scotland.
Well written though they are, and relatively light on baffling jargon, they are not an easy read.
You can find them here:
At the risk of simplifying what they are saying it amounts to this.
Scotland will be bound by spending rules if she becomes independent and is able to use the pound Sterling as her currency - something the UK government has cast doubt over.
In other words there will be constraints on spending. An independent Scotland will not be able to spend, spend, spend. Most sensible people never thought she would be able to.
The question then is what can an independent Scotland do? SNP ministers say that it will have the flexibility to use the tax system to promote equality and stimulate economic growth.
The Commission reports today seek to try to explain in a bit more depth how they might do that.
One issue they raise is that the tax system could be used to make the system fairer which, citing polling evidence, they say is what Scots want.
What they do not say is precisely how this might be done though there is a hint about widening the tax base - again they do not say exactly what that means.
However, if you widen the tax base that means taxing people, or businesses, more broadly. Would that mean higher taxes, or new taxes?
Best not to speculate on what the SNP would do were it to win the independence referendum, and then win the subsequent election, but SNP ministers are bound to be asked for more detail on this.
The Commission also says that independence could also mean a simplification of the very complex UK tax system with the possible integration of the tax and benefits system.
Most experts would say "hear, hear" to that. But successive UK governments have said similar things and found the complexity devilishly difficult to simplify.
What is perhaps most clear - and this has become a theme across the independence debate - is that change, if independence comes, will be evolutionary, not revolutionary.
Opponents of independence are likely to argue that the SNP cannot continue to promise tax cuts for businesses - opening up a potential difference north and south of the Border - and the levels of state funding the Nationalists appear to want to continue.
They will also say that there is no guarantee that the independent Scottish government could come to an agreement with what by then would be known as the rest of the UK (rUK) over using the pound.
And if they did, the opponents of independence argue, the conditions imposed by rUK would be so severe as to restrain the Scots spending ambitions. Just look at the way the EU dictates spending to the likes of Greece and Ireland they say.
This debate will run and run, right up to the independence referendum. The Commission has shed some more light on the detail but more is needed before voters are able to make up their minds on whether to back independence.
They can be sure of death. They also want to be sure on taxes.