"I do not have the capacity to indulge in the romanticism that like Berlin Wall, one day the differences may go. How the course of history will take turn, nobody can predict with that precision. It may happen", he said here last night at the launch of eminent journalist M J Akbar's book "Tinderbox--The Past and Future of Pakistan".

He said the collapse of the Berlin Wall and formation of the European Union were not foreseen but took place.

"Yes, the Berlin Wall collapsed. Yes, the EU has come together, which began with a limited approach and objective of having some trade relations. It has united...side by side there are other examples also which we have seen with our own eyes- how a mighty unified structure (Soviet Union) has collapsed just after seven decades.

"How a composite state created after the second World War has dismembered into three or four states within a short span of 10-15 years," Mukherjee said.

The senior Congress leader said one can be selective in choosing friends but not neighbours.

"Most of us will agree that we cannot wish away our neighbours. We can choose our friends, we can be selective in choosing our friends....But neighbours are there where they are. I cannot simply wish them away. Those days are gone when one could have displaced them by force," Mukherjee said.

Describing Pakistan as India's "most important" neighbour, he said, "The stability and well-being of Pakistan" is in the interest of this country as the two could not develop and prosper in isolation today.

"The basic question before every Indian policy-maker is whether we should live with our neighbour in perpetual tension or try to live in peace. And fortunately, there is a broad consensus across the political spectrum on these issues," Mukherjee said.

The senior Congress leader said the two neighbouring countries may have "insurmountable problems" but Pakistan was India's "most important neighbour".

"It is essential if we have to deal with our neighbour, we have to know what they are, who they are," Mukherjee said.

"I do not believe a nation state can simply wither," Mukherjee said, in an apparent reference to apprehensions often expressed about the future of Pakistan as a nation.