Bill

From the article you linked to:

"If a retiree can live entirely on dividend income and not invade capital, then price level drawdowns aren’t as important in the question of outliving your assets as the dividend growth level versus inflation.

Of course, for retirees, who must utilize both income and capital to survive, price level is important, because multi-year price declines combined with fixed dollar consumption of capital can deplete a portfolio. Those investors are at a higher risk of outliving their assets."

It actually is pretty simple.  Calculus is not required to understand and benefit from these concepts.

Regards.

Cliff