CONSTITUTIONS are state-building documents. They establish the institutions of the state.

Constitutions typically set out how Parliament is ­elected and when and how elections take place. They specify how Governments are chosen and ­removed, the composition of the Cabinet, and the role of the Head of State. They maintain the neutrality and independence of the ­judiciary, the ­impartiality and professionalism of the civil service, and the integrity of bodies such as the Electoral ­Commission and Boundaries ­Commission. They regulate relationships between these ­institutions.

We can understand a constitution, in these institutional aspects, as something like the ­blueprint of a governing machine – or perhaps as its operating manual. Yet nations are not ­machines. They are communities. They are held together by their institutions, but also by ­memories, songs, places, sentiments.

A constitution is necessary in a democracy, but there must first be a demos, a people bound together by a shared sense that they have ­important things in common.

So constitutions are also nation-building ­documents. They say something about a ­nation’s history, its identity, its aspirations, its place in the world. They are totem poles: a shared point of reference, transcending party, region, ­religion, gender, or class, around which the ­nation can gather and unite, recognise itself, and recollect itself.

Constitutions do this nation-building work in various ways. Many contain a preamble, a kind of introduction to the constitution. The ­preamble is the place for the rhetorical heart-stirring stuff, before the constitution gets down to the dull but important things like the ­composition of the Public Service Commission.

Preambles provide an opportunity for the constitution to tell its own story – where does it come from? Where is it going? What sort of society is it trying to create? Some are short and pithy: the preamble to the United States Constitution is condensed into just 52 words. Others wax lyrical for pages, recounting past battles, honouring struggles for national liberation, praising long-dead national heroes, or reciting allegiance to God, Liberty, Justice, ­Democracy, Marxist-Leninism, or whatever ideological ground the state claims to stand upon.

Constitutions can also proclaim national ­identity in other ways. Often they include ­provisions on the national flag, the national ­anthem, the national motto, and other symbols of nationhood. These may be controversial, and the decision of which symbol to adopt can be politically fraught. In Sudan, some democrats wanted to return to the blue-yellow-green flag adopted in 1956, in place of the Pan-Arabist flag adopted by later authoritarian regimes.

The French Constitution of 1830 boldly declared, “La France reprend ses couleurs” – France retakes its colours – meaning a return to the revolutionary tricolour, expressing the ­values of liberty, equality and fraternity, in place of the dynastic flag of the Bourbon kings.

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Values, principles and markers of identity may also be buried in the substantive ­provisions of the constitutional text. Constitutionally ­protected fundamental rights, for example, aside from their strictly juridical function, also have rhetorical value. They say something about who we are and what we collectively stand for as a nation: “We are a people who are committed to treating everyone with dignity and respect, to protecting the poor and weak, to caring for the land and nature.”

The same is true of Principles of Public Life: “We are a people who believe in honesty and integrity, and demand that of our political ­leaders.”

Even the question of whether to have a ­monarch or not is primarily a matter of ­symbolism and identity: do we associate ­ourselves with the culture and values that the monarchy has come to represent, or do we ­repudiate those values?

Such constitutional provisions are part of a wider phenomenon of what might be termed “constitutional symbology”. This includes things that are unlikely to be mentioned in or regulated by the constitution, but ­nevertheless form part of the state’s official projection of ­national identity. Whose pictures are on the banknotes and the coins? Who is on the stamps? Which public holidays are ­celebrated? Should the Scottish Navy call its flagship ­William ­Wallace or Donald Dewar?

Such symbolism can be deliberately ­calculated to promote partisan objectives. The last ­Labour Government instituted Armed Forces Day in an attempt to shore-up the Union.

It can also a means of reconciliation. South Africa’s post-apartheid flag and anthem were designed to be as conciliatory and unifying as possible.

There is lots of serious practical work to be done on constituting a modern democratic ­Scotland. But spare a thought for those who will one day have to decide what the national anthem should be, or whether to rename every Union Street in Scotland.