the stuff of greatness

1. The qualities or characteristics that make someone or something great. You will face huge challenges as the company's leader, but overcoming adversity is the stuff of greatness. Anger and spite are easy, seductive reactions to have when we are mistreated, but magnanimity? Now that's the stuff of greatness.

2. That which is especially remarkable, outstanding, or extraordinary. The majority of the film is a bit meandering, to be honest. But that final act—my goodness, it's the stuff of greatness! The restaurant may not be much to look at, but the food they serve is the stuff of greatness.