It is fitting to have a Ben Graham quote open this essay because I owe so much of what I know about investing to him. I will talk more about Ben a bit later, and I will even sooner talk about common stocks. But let me first tell you about two small nonstock investments that I made long ago. Though neither changed my net worth by much, they are instructive.

This tale begins in Nebraska. From 1973 to 1981, the Midwest experienced an explosion in farm prices, caused by a widespread belief that runaway inflation was coming and fueled by the lending policies of small rural banks. Then the bubble burst, bringing price declines of 50% or more that devastated both leveraged farmers and their lenders. Five times as many Iowa and Nebraska banks failed in that bubble’s aftermath as in our recent Great Recession.

In 1986, I purchased a 400-acre farm, located 50 miles north of Omaha, from the FDIC. It cost me $280,000, considerably less than what a failed bank had lent against the farm a few years earlier. I knew nothing about operating a farm. But I have a son who loves farming, and I learned from him both how many bushels of corn and soybeans the farm would produce and what the operating expenses would be. From these estimates, I calculated the normalized return from the farm to then be about 10%. I also thought it was likely that productivity would improve over time and that crop prices would move higher as well. Both expectations proved out.

I needed no unusual knowledge or intelligence to conclude that the investment had no downside and potentially had substantial upside. There would, of course, be the occasional bad crop, and prices would sometimes disappoint. But so what? There would be some unusually good years as well, and I would never be under any pressure to sell the property. Now, 28 years later, the farm has tripled its earnings and is worth five times or more what I paid. I still know nothing about farming and recently made just my second visit to the farm.

In 1993, I made another small investment. Larry Silverstein, Salomon’s landlord when I was the company’s CEO, told me about a New York retail property adjacent to New York University that the Resolution Trust Corp. was selling. Again, a bubble had popped — this one involving commercial real estate — and the RTC had been created to dispose of the assets of failed savings institutions whose optimistic lending practices had fueled the folly.

Here, too, the analysis was simple. As had been the case with the farm, the unleveraged current yield from the property was about 10%. But the property had been undermanaged by the RTC, and its income would increase when several vacant stores were leased. Even more important, the largest tenant — who occupied around 20% of the project’s space — was paying rent of about $5 per foot, whereas other tenants averaged $70. The expiration of this bargain lease in nine years was certain to provide a major boost to earnings. The property’s location was also superb: NYU wasn’t going anywhere.

I joined a small group — including Larry and my friend Fred Rose — in purchasing the building. Fred was an experienced, high-grade real estate investor who, with his family, would manage the property. And manage it they did. As old leases expired, earnings tripled. Annual distributions now exceed 35% of our initial equity investment. Moreover, our original mortgage was refinanced in 1996 and again in 1999, moves that allowed several special distributions totaling more than 150% of what we had invested. I’ve yet to view the property.

Income from both the farm and the NYU real estate will probably increase in decades to come. Though the gains won’t be dramatic, the two investments will be solid and satisfactory holdings for my lifetime and, subsequently, for my children and grandchildren.

I tell these tales to illustrate certain fundamentals of investing:

You don’t need to be an expert in order to achieve satisfactory investment returns. But if you aren’t, you must recognize your limitations and follow a course certain to work reasonably well. Keep things simple and don’t swing for the fences. When promised quick profits, respond with a quick “no.”

Focus on the future productivity of the asset you are considering. If you don’t feel comfortable making a rough estimate of the asset’s future earnings, just forget it and move on. No one has the ability to evaluate every investment possibility. But omniscience isn’t necessary; you only need to understand the actions you undertake.

If you instead focus on the prospective price change of a contemplated purchase, you are speculating. There is nothing improper about that. I know, however, that I am unable to speculate successfully, and I am skeptical of those who claim sustained success at doing so. Half of all coin-flippers will win their first toss; none of those winners has an expectation of profit if he continues to play the game. And the fact that a given asset has appreciated in the recent past is never a reason to buy it.