Numbers guide much of our daily lives. From the price of a gallon of gas to the cost of our morning coffee, numbers are solidly submerged in our collective consciousness. Numbers are absolute. Even though the cost of a gallon of milk may go up or go down, what the numbers involved mean stay static and absolute. Prices may fluctuate, but a dollar is still four quarters, ten dimes, twenty nickels or one hundred pennies (as unwieldy and impractical counting all of them out at the coffee shop cash register might be). Numbers are logical and predictable. Three times seven will always add up to twenty-one (a number that has much significance at the blackjack table and equal importance for college students looking to embrace their new-found adulthood with a pint or two at the local watering hole). Numbers are practical and unemotional. Numbers know no sympathy - just ask anyone who has ever gotten a costly ticket for exceeding a posted speed limit. Numbers are a lot of things but one thing they are certainly not: numbers are not people.

It will soon be the 10-year anniversary of when, in early October 2007, the S&P 500 Index hit what was its highest point before losing more than half its value over the next year and a half during the global financial crisis.

Over the coming weeks and months, as other anniversaries of major crisis-related events pass (for example, 10 years since the bank run on Northern Rock or 10 years since the collapse of Lehman Brothers), there will likely be a steady stream of retrospectives on what happened as well as opinions on how the environment today may be similar or different from the period leading up to the crisis. It is difficult to draw useful conclusions based on such observations; financial markets have a habit of behaving unpredictably in the short run. There are, however, important lessons that investors might be well-served to remember: Capital markets have rewarded investors over the long term, and having an investment approach you can stick with—especially during tough times—may better prepare you for the next crisis and its aftermath.