Background and Concepts
This was a lecture given by the Swiss-French thinker Benjamin Constant in 1819 (the French title is "De la Liberté des Anciens Comparée à celle des Modernes"). Alternative dates for it as a printed essay are sometimes given, because Constant had previously used much of the material contained in it. Common attributions include 1812 and 1816. The substance of the lecture is very important for the history of political thought, as it is the first instance of the now-common distinction between what 20th century academics called negative liberty and positive liberty. Constant does not describe it in these terms, but Isaiah Berlin's famous lecture on the subject clearly echoes Constant's own distinction between ancient and modern liberty.
Ancient liberty, according to Constant, involved participating in government and sovereignty. Compatible with this collective freedom was the complete subjection of the individual to the authority of the community. Modern liberty, by contrast, was the right to be free from arbitrary arrest and punishment, the right to free speech, to hold property, to move and associate freely and to choose one's religion. In other words, the liberty of the moderns is that liberty we see enshrined in documents like the American Bill of Rights, as well as in many other constitutions.
Constant was writing in the wake of the first French Revolution, and was well aware of the excesses of some of its major protagonists. He attributed these excesses not to evil natures, though, but to an attempt to "force France to enjoy the good she did not want, and denied her the good which she did want". That is, they tried to free people to govern themselves and become sovereign, when all they really wanted was the freedom to be left to their own affairs.
One of the motivations behind the essay is Constant's desire to defend representative government against its detractors, both the radical democrats of the revolution and the revived monarchists, as being the government most suited to people in the modern age. He considered first why this form of government had been completely unknown among ancient republics, to the extent that "the ancient people could neither feel the need for it nor appreciate its advantages." He argues that this results largely from the form of freedom known to the ancients. As each citizen was involved in government (n.b. citizenship didn't include women, the poor, slaves or resident aliens), they felt more able to let the government do what it wanted: "Thus among the ancients the individual, almost always sovereign in public affairs, was a slave in all his private relations". Interestingly, John Stuart Mill would later make a very similar point in "On Liberty", arguing that people who had managed to free themselves from tyrannical authoritarian governments had failed to see the extent to which democracies paved the way for a tyranny of the majority.
Differences between ancient republics and modern democracies
Conducive to this attitude among the ancients, Constant noted, was the fact that ancient republics were tiny - the largest was smaller than any modern state - and therefore war-like, always desiring each other's territory. Furthermore, all these states had slaves, who would do most of the work, allowing citizens the leisure to discuss affairs of government. Apart from the size of state territories having grown, Constant believes that the major difference between ancient and modern times is the new importance of commerce. He thought that experience had proved that the burdens of war weren't really worth it; while commerce provided a milder and surer means of getting what one wants - that is, war and commerce have the same goal, but commerce achieves it better. Moreover, the abolition of slavery (which of course had not actually been abolished in every state when Constant was writing) meant that all needed to work, with no time to spend in public square every day. Commerce itself leaves very little free time, as those in business rarely want to be distracted from it (something we see in people voluntarily working in the office for 19 hours a day, perhaps).
Commerce also works to create the love of independence which is the foundation of 'modern liberty'. For commercial activity supplies needs and satisfies desires, without the intervention of government. This intervention instead comes to be resented. Constant seems, for a moment, to hold up the flame for modern conservatism when he says "every time governments pretend to do our own business, they do it more incompetently and expensively than we would".
Modern people no longer have the time to enjoy the liberty of the ancients and, even if they did, Constant believes, modern states are of such a size that the contribution of each citizen to government would be very small and unsatisfying to the individual. Thus it would still leave citizens with a need to find their satisfaction elsewhere. In place of this ancient freedom, then, modern freedom provides people with peaceful enjoyment and private independence, allowing them to find their satisfactions in private life rather than the public square.
Conclusions in the wake of revolution
The revolutionaries had failed to realise this, being spurred on by the spirit of ancient texts, as well as by modern writers equally so influenced, such as Jean-Jacques Rousseau who, Constant argued, had transposed into the modern age a collective sovereignty which belonged to other centuries and which would, in the modern age, only provide a pretext for tyranny. What the revolutionaries found, when they tried to implement these ideals was that people did not find a small share in an abstract sovereignty was worth the sacrifices it required from them. Here Constant comes again to defend representative government, saying that "poor men look after themselves, rich men hire stewards". People still want their interests to be defended, but they don't have time to do it themselves.
Constant is not, however, a mere apologist for the march of progress. He thinks that the spirit of the age in modernity has its own dangers, and just as sensible rich men keep an eye on their stewards, so we must keep an eye on our representatives. In caring only about our private concerns we might give up our political liberties too easily. These liberties are important, though, as they contribute to our self-development. Rather than renouncing either ancient or modern liberty, Constant thinks that it is necessary to learn to combine them.
This lecture, then, was important, because at the turn of the 19th century it provided a foundational text for liberalism, conservatism and all the theorists of representative government. As can be seen from Isaiah Berlin's takeover of the distinction in "Two Concepts of Liberty", the distinction between a liberty of political involvement and a liberty of personal freedom continued to be important to political theorists into the 20th century, and shows no sign of disappearing in the 21st.