"In the long run we are all dead," the most famous economist of all time, John Maynard Keynes, famously said.
Keynes (1883-1946) ultimately proved the point.
Nonetheless, the debate about what he 'actually meant' by this continues to rage today. But in short, Keynes was arguing for economists to pay more attention to the present rather than floating idealised models of the distant future.
This is exactly the opposite of standard investment advice, which urges investors to ignore short-term noise in favour of long-term goals.
Investment markets are noisy, however, and getting noisier (much like that concrete cutter across the road from me).
For example, high-frequency trading algorithms have amped up the volume while reducing the short-term to fractions of a second. (This can't go on forever. Modern physics has put an absolute limit on the short-term - the planck time - but how about 'planck+2'?)
It's not easy being a long-run investor, even for those who do it for a living, as the just-published 'Long term portfolio guide' makes clear.
The report, prepared by a recently-formed institutional investment collective - Focusing Capital on the Long Term (FCLT) - lays out some comprehensive rules for sticking-it-out.
Based on input from over 20 global investment groups, including the New Zealand Superannuation Fund (NZS), the FCLT study hones in on five key areas: investment beliefs; risk appetite; benchmarking; evaluations and incentives; and, investment mandates.
And while the report is obviously aimed at professionals, David Iverson, NZS head of asset allocation, says there are some key lessons for retail investors too.
For instance, Iverson says retail investors also need to define their investment beliefs and develop strategies and disciplines to carry them through the long term - whatever that may be.
"We define the long term as the ability to hold investments as long as you wish," Iverson says.
As well as a producer of pithy quotes, Keynes was also an investor - and a pretty good one, according to this report.
"Keynes believed in holding investments for the long term," the report says, a lesson he apparently learnt while managing money for a university endowment fund.
"Portfolio turnover averaged 56 per cent during approximately the first half of the period of his management, falling to only 14 per cent in the second (and more successful) half," the article says.
In the long run, Keynes achieved average annual returns of 16 per cent, compared with 10.4 per cent for a market benchmark for his fund over the period from 1922 until he died.