There’s an old proverb that says, “We must eat a peck of dirt before we die.” What this means is that just as no one can escape eating a certain amount of dirt on their food, everyone must endure a number of unpleasant things in his or her lifetime.

A peck is about two gallons, which would be a lot of dirt if you had to eat it all at once. But over a lifetime the few grains of soil you eat on your apple or the dust from the candy that fell on the floor (within the five-second-rule) adds up. This peck of dirt not only won’t kill you (probably) it can even make you stronger.

As medical science and old wives’ tales will confirm, children need exposure to dirt—or more precisely the parasites and infectious agents found in dirt—to build a healthy immune system. This is known as the “hygiene hypothesis” and it explains why the children with helicopter parents who buy hand sanitizer by the gallon have perpetually snotty noses.The kids are too clean for their own good.

This same hygiene hypothesis can also apply to our moral lives. That’s why we shouldn’t always protect children from the pain of life. By “eating a little dirt” now and then, they e more resilient to the hardships of life.

Supreme Court Justice John Roberts recently gave mencement speech at his son’s 9th grade graduation. Although he doesn’t say so directly, his advice to the graduates is that they need to eat a little dirt:

Now mencement speakers will typically also wish you good luck and extend good wishes to you. I will not do that, and I’ll tell you why. From time to time in the years e, I hope you will be treated unfairly, so that you e to know the value of justice. I hope that you will suffer betrayal because that will teach you the importance of loyalty. Sorry to say, but I hope you will be lonely from time to time so that you don’t take friends for granted. I wish you bad luck, again, from time to time so that you will be conscious of the role of chance in life and understand that your success is pletely deserved and that the failure of others is pletely deserved either. And when you lose, as you will from time to time, I hope every now and then, your opponent will gloat over your failure. It is a way for you to understand the importance of sportsmanship. I hope you’ll be ignored so you know the importance of listening to others, and I hope you will have just enough pain to passion.

Whether I wish these things or not, they’re going to happen. And whether you benefit from them or not will depend upon your ability to see the message in your misfortunes.

You can read the rest of Justice Robert’s speech here.