I am not a psychologist, nor am I a philosopher. But I’ve spent a lot of time thinking about the goals we pursue, the things we own, and the items we buy. I find it to be a fascinating study into the human spirit.

There are countless reasons we buy more stuff than we need. Some motivations are pushed upon us by society. But other causes seem to spring from our own internal motivations. Either way, arriving at a healthy understanding of why we buy more than we need is a worthy pursuit.

Which is one reason I find the Diderot Effect to be such an interesting phenomenon. This motivation for overconsumption, originally noted in the 18th Century by a French philosopher named Denis Diderot, is still commonplace among us.

The simplest description of the Diderot Effect is this: “the introduction of a new possession into a consumer’s existence will often result in a process of spiraling consumption.”

In other words, the purchase of one new item often leads to the purchase of another. We can see this play out in small ways:

Last week, my wife took my 9-year old daughter school shopping for the upcoming year. On her shopping list was a new backpack. After viewing her choices, my daughter chose one. But this new backpack does not match the lunch bag she used last year—and so, almost immediately, “new lunch bag” was added to the shopping list, even though her lunch bag from last year still worked just fine.

The introduction of a new item (the backpack) resulted in a desire for further consumption. But this, as I mentioned, is only a small example.

There are more examples of the Diderot Effect all around us:

We buy a new shirt or dress… and immediately begin looking for new shoes to match, instead of maintaining a minimalist wardrobe.

We bring home a new couch… and suddenly the end tables in our living room appear old and shabby, in need of replacement.

We purchase a new car… and soon begin spending money on car washes, more expensive gasoline, or a parking pass.

We move into a new home… and use the occasion to replace our existing bedroom set with a new one.

In each circumstance, the reality is that we already owned enough shoes and our end tables and bedroom furniture worked just fine before. But because something new had been introduced into our lives, we were immediately drawn into a process of spiraling consumption.

Denis Diderot observed and noted this phenomenon in an essay titled, “Regrets on Parting with My Old Dressing Gown.” In the fictional story, he receives a new, elegant dressing gown from his friend, a kind gesture. However, upon receiving the gown, Denis notices all his other possessions begin to look drab and faded compared to it. He begins replacing them—all of them—even the art on the walls. And by the end of story, Denis notes, “I was absolute master of my old dressing gown, but I have become a slave to my new one.”

In this way, Diderot explains how new consumption often leads to further consumption. But more than that, he argues that we begin identifying with our possessions and search for new things that fit into our specific mold. The purchase of fashion, he would argue, is rarely about the functional use of clothing—it’s not just about finding thread to cover our bodies. Instead, the purchase of clothing (and everything else) represents an opportunity for self-expression.

But for this piece, I am more interested in the idea of over accumulation, how purchases often lead to more, unplanned purchases. Because once you understand the principle, you can begin to break its cycle.

How then might we overcome the Diderot Effect in our lives and resist this pattern of unnecessary consumerism? Let me offer some thoughts:

1. Become aware it is happening. Observe when you are being drawn into spiraling consumption not because you are in actual need of an item, but only because something new has been introduced.

2. Analyze and predict the full cost of future purchases. A store may be having a great sale on a new outfit—but if the new outfit compels you to buy a new pair of shoes or handbag to match, it just became a more expensive purchase than originally assumed.

3. Avoid unnecessary new purchases. Realize the Diderot Effect is a significant force and overcoming it is very difficult. You may avoid replacing those end tables at first, but eventually, at some point down the road, you are going to break down and buy new ones that better match the new couch. There are times when we have a legitimate need to buy new things. But the best way to overcome the Diderot Effect is to never allow it to overpower you in the first place.

4. Remind yourself that possessions do not define you. The abundance of life is not found in the things that you own. Your possessions do not define you or your success—no matter what marketers will try to tell you.

5. Buy things for their usefulness rather than their status. Stop trying to impress others with your stuff and start trying to impress them with your life.

Notice the Diderot Effect in your own life. Soon, as you begin to recognize it around you, it will become one less cause of unnecessary consumerism in your home and wallet (assuming that wallet already matches your handbag).