The following is an excerpt from The Motley Fool newsletter “Bilanz Ziehen.” Simply click here to register for free.

I spent last weekend thinking about what I could write about for this first-ever issue of Bilanz Ziehen. I could have gone straight to stock picks and shared a stock currently on my watchlist. Or I could have provided my perspective on what’s going on in the stock market right now.

Both of those things are important, and both will be an ongoing part of Bilanz Ziehen. But I decided not to do either.

Instead, I thought it best to start with the big picture.

When I say “big picture,” I mean the things that can make the biggest difference in your investing over the long term. And for this letter specifically, I’m talking about two questions that you can ask that could completely change the way you think about the companies you own.

Those two questions are:

  1. Are customers better off because this company was created?
  2. Would customers be worse off if this company no longer existed?

At first this may seem like two ways of asking the same question. But the two questions are subtly different, and that subtle difference is important.

The first question asks whether the company has created something of great value, or maybe even spearheaded the development of a whole new industry. I think customers are better off because of Yahoo! (FRA: YHO) existence. It was an early giant in internet search and helped drive that industry forward.

The second question, meanwhile, gets to the lasting power of the company, its products, and its brand. Regarding Yahoo, the world probably wouldn’t be all that much worse off if it disappeared today. (Sorry, Yahoo). Many other search companies have come along since those early days, including the market-dominating Google  (ETR: GGQ7). Today, Yahoo doesn’t even have its own search technology – it gets that from Microsoft’s (FRA: MSF) Bing.

No easy answers

There’s no “right” or “wrong” answer to these questions for any given company. One investors may say that Adidas (ETR: ADS) is a clear “yes” on both questions. Another might think that the company gets one “yes”, at best.

Unlike calculating a price-to-earnings ratio, which can be figured out based on readily-available data, these questions are a thought exercise. To some extent, the answers that you come to aren’t as important as reasoning process you go through along the way.

You will, however, come to an answer in the end. The answer itself — whether you answered “yes” or “no” to each of the questions — is obviously important. But it’s also important to note how easy or hard it was to get to each of the answers. For me, I have to think barely half of a second about whether customers are better off because of Tesla (ETR: TL0) and Apple (FRA: APC). It’s an easy “yes” on both. But what about Deutsche Bank (ETR: DBK)? That would take a lot more thought and perhaps some finagling to possibly get to a “yes.”

The Foolish way

Thinking about investing the Foolish way means thinking about the long term. Our primary concern isn’t what will happen in the next year, six months, six weeks, and definitely not in the next six minutes. Instead, we’re thinking in terms of five years, 10 years, or even 20 years.

When thinking in those terms, it becomes obvious that we don’t want to just invest in “any old company.” We want to invest in the best companies. These are the companies that we can expect not only to be around multiple decades from now, but to be thriving multiple decades from now.

There’s a lot involved in finding great investments, but if you start with these two simple questions, you’re starting off right.

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Matt Koppenheffer owns shares of Apple. The Motley Fool recommends Apple, Google (C shares), Tesla Motors, and Yahoo. The Motley Fool owns shares of Apple, Deutsche Bank, Google (C shares), Microsoft, Tesla Motors, and Yahoo.