Unification is an idea that moves most Koreans, North and South, on an emotional level.
For some, especially young people in the South, it may not be a burning issue. Details like the costs, the risks and what specifically both sides stand to gain are rarely given much thought by anyone who isn't an academic, politician or activist.
But when North Korean leader Kim Jong Un and South Korean President Moon Jae-in meet Friday, the prospect of unification, even if only in the abstract, will loom large around them.
Can Kim's nuclear-armed North and the K-pop capitalism of Moon's South ever merge into one Korea? Both leaders come to the table with distinct visions of what that would look like. And they are very different.
Republic of Koryo
After failing to take the South by force in the 1950s, North Korea's founder and "eternal president,'' Kim Il Sung, announced in 1980 a plan for what he thought a unified Korea should look like.
He called it the Democratic Federal Republic of Koryo. Koryo was an ancient Korean kingdom from which the word Korea is derived.
Kim's plan was for an arrangement something along the lines of what Hong Kong has with China — a unified nation with two separate systems of government.
Under his plan, the North and South would respect each other's ideology, social system and autonomy. Both sides would have an equal number of representatives in a supreme national assembly with equal rights and responsibilities. The assembly would also have representatives of Koreans overseas. It would have a standing committee that would administer state affairs.
Kim stressed the need for this new federation to remain neutral and independent, avoiding in particular military alliances with others.
Not surprisingly, that looks a lot like North Korea today, with its Supreme People's Assembly, and the party's Politburo and Central Committee overseeing day-to-day policies. Even the name smacks of the North, which is officially the Democratic People's Republic of Korea.
An equal number of assembly seats would be a good deal for the North, which has half the South's population. The inclusion of Koreans overseas would boost that advantage even further since, for historical reasons, more often than not they have at least nominal allegiance to Pyongyang, not Seoul.
With so many devils lurking in the details, Kim's grand plan has never gotten much traction.
A Korean commonwealth
South Korea's three-step proposal ends in a similarly predictable place: its own system writ large across the peninsula.
The first priority, according to South Korea's Unification Ministry, is to develop a sustainable relationship and resolve the issue of North Korea's development of nuclear weapons.
Seoul wants to substitute the unstable armistice that ended the fighting of the 1950-53 Korean War with a permanent peace treaty — a goal Pyongyang shares. This step could get a boost on Friday. It will almost certainly be taken up then and probably again at the summit between Kim and President Donald Trump in May or early June.
South Korea wants to then develop trust and cooperation to the point where a sort of national consensus has been achieved. After a transitional commonwealth period, the next step would be the formation of a single market on the Korean Peninsula "to create new growth engines and create an inter-Korean economic community of coexistence and co-prosperity.''
"We will build a new economic order that will bring peace and prosperity to the Korean Peninsula and Northeast Asia,'' the ministry concludes.
Gradual, peaceful progress
The essentials of this plan were announced by President Roh Tae-woo in September 1989.
The succession of administrations that have taken office in the South since Roh have adhered fairly predictably to the principle of gradual, peaceful progress, while calibrating their willingness to engage with Pyongyang based on their assessment of its level of vulnerability or hostility.
In the long run, however, it makes no provision for a one-state, two-system future.
Ultimately, Seoul believes, the North Korean system has to go.