Our national output figures tell us the value of the goods and services we produce for sale, and our employment figures tell us how many people work for pay.
Yet because it is very difficult to estimate the scale of any human activity that is not measurable in money terms, we simply don't know how much unpaid work people also undertake, or how many people engage in voluntary service.
Indeed, the point has frequently been made that if those undertaking domestic work were paid for it by members of their families, this would hugely increase measurable national output.
Or, put another way, the failure to place a value on this domestic work because of the absence of financial transactions within the home leads to a gross under-valuation of total national output.
But what about other forms of voluntary work - the services that so many people render free to fellow human beings outside the family?
We know absolutely nothing about the scale of this kind of work, nor about the relative importance of such activity in different countries.
In democracies an important part of voluntary work is undertaken within the political system by party supporters.
The rest of the population is often unconscious of, and I believe greatly undervalues, the importance to society of this kind of voluntary activity.
Without it voters would not have the same opportunity to make free and informed choices between alternative candidates for public office.
The vast majority of those who undertake voluntary political work neither expect to receive nor ever do receive any benefit from their work.
This work is often very boring between elections, and at election times is frenetic and often exhausting. Their labour is, perhaps, one of the most undervalued of all forms of voluntary public service.
How many people engage voluntarily in the political process?
I recall that an extensive survey carried out in 1969 (the results of which I analysed for what I think may have been the first of Vincent Browne's many journalistic ventures, Nusight magazine), suggested that at that time about 6 per cent of the adult population were members of political parties. Most of these would have played some role in the general election of that year.
I suspect that party membership may be somewhat lower today than then; perhaps 4 per cent of those aged 18 to 65. This would not be much more than 100,000 people.
Many of these will be office-holders in local party branches, delegates to party conferences, or delegates to conventions at which candidates will be chosen to stand for election to local authorities, the Dáil or the European Parliament.
Except where a dispute breaks out, very little of intra-party activity ever reaches the ears of the public as the media are preoccupied with the activities of elected representatives, especially in the Dáil.
The lack of media coverage of activity within political parties can sometimes lead to the public being surprised at the scale of political shifts at national level.
An example of this occurred just two years ago when the media had been busy writing off Fine Gael as having no future. This happened at the very time when that party was about to make a remarkable leap forward by winning a record 293 council seats to Fianna Fáil's 302 in the local elections of June 2004.
I have to say that, having been outside politics for the previous 12 years, I was almost as surprised as everyone else at the scale of Fine Gael's success in those elections.
It was only when I examined in some detail the results in the 180 local constituencies that I came to realise the magnitude of this achievement.
It was remarkable in terms of the recovery it reflected in constituency organisation, in candidate selection, in electoral strategy, and in party morale during the two years following that party's defeat in the Dáil election of 2002.
After the 1977 defeat of the national coalition government - when I found myself, to my own surprise, elected unanimously by the Fine Gael parliamentary party as its leader - I engaged upon a similar reorganisation. As a result of this the party won 23 extra seats at the following election and entered government with Labour.
Up to that time my interest was mainly in policy issues, and I have to say that I was surprised at the enjoyment I derived from visiting over 40 constituencies and devising a radical revision of the party's constitution to free up the potential energy of its members.
This also removed obstacles within the system to the selection of able candidates for office.
This allowed for 14 women to be elected to the Dáil or Seanad in the course of the three general elections of 1981 and 1982.
Incidentally, during these visits I took the initiative in organising indoor meetings everywhere, which for some reason had not previously been a feature of the Irish party system, which had become very inward-looking.
Meeting some 25,000 people, I could draw from a wide range of political opinion, including public representatives of other political parties, a number of whom attended these meetings.
Responding to some 1,000 questions from the floor, it gave me as a Dubliner valuable insights into public opinion outside the capital city.
Having led a political party for almost 10 years, I am better placed than most to understand how much in politics depends upon the skill with which voluntary organisers lead local party organisations.
I can also vouch for the enthusiasm of a party's voluntary workers.
Tonight, in a temporary reversion to my former political persona, I shall be joining at a dinner in Dublin a key band of voluntary workers.
This group is the surviving Fine Gael constituency organisers of 25 years ago, and together we will pay tribute to Peter Prendergast, the extraordinarily successful national organiser and general secretary of Fine Gael from 1977 to 1981.
This occasion will also enable me, through this remarkable band of former constituency organisers, to thank retrospectively the tens of thousands of voluntary workers whose efforts produced the election outcomes of the 1980s.