It is possible that population is destiny, other things equal, but other things are never equal.
And so a plague here, or a fateful decision by a Chinese emperor there, can set a region down a path that wipes out the advantages of population.
Perhaps those advantages must be harnessed by the right sorts of institutions,
or an accommodating culture—which take far longer to develop or adopt than technologies do to emerge.
There is no academic consensus regarding what determines economic fortunes over long time horizons, important though the question is.
Alternatively, one might argue that conditions have changed in ways that amplify the power of population.
A billion brains seem a more economically potent force in an era of mass education, in contrast to the mass illiteracy that prevailed in the past.
But crucially, Asia's recent rise has not been the result of a spurt of indigenous innovation given its impetus by the size of its population.
Rather, it has happened as part of a wave of globalisation, which aided the transfer of technological know-how.
Openness to exchanges of goods and ideas, or indeed to immigration, is not an immutable parameter,
but subject to change based on human preferences.
Mr Desmet and his co-authors reckon that eliminating all barriers to migration would raise global welfare threefold—
an extraordinary figure that reflects yawning differences in output per person between countries, and the unrealised human potential they represent.
As intriguing as it is to consider the directions in which macro variables such as population or GDP are likely to nudge the world in coming centuries,
it is human decisions that will determine which places and people are given the opportunity to become rich.
National populations matter to the extent that borders do.
It is a depressing notion, but a plausible one, that in half a millennium's time they will matter still.
A cholera plague had been killing many prisoners of war at the time.
There is a general consensus among teachers about the need for greater security in schools.
Her anxiety about the world was amplifying her personal fears about her future.
Nothing in the world is immutable.