As the 105th day of the Gregorian calendar, April 15 brings with it a sense of apprehension and urgency for many United States residents. On this day, Tax Day, Americans must submit their individual federal tax returns or file for an extension. Stories of long lines at the post office will flood the news as procrastinators rush to avoid penalty for their negligence. But April 15 serves as more than just a deadline.

The ancient Romans observed the Fordicidia on April 15, a festival of fertility involving the sacrifice of a pregnant cow. On an international scale, World Art Day, first celebrated in 2012, promotes the appreciation of art and creativity. In the world of Major League Baseball, we celebrate Jackie Robinson Day.

Jackie Robinson played his first Major League game with the Brooklyn Dodgers on April 15, 1947, making him the first black Major League ballplayer of the modern era. To this day, we celebrate the courage and resilience it took to step out on that field and endure a season full of mixed feelings, ranging from hopeful excitement, to cautious tolerance, to unadulterated hatred. While a myriad of books and movies strive to depict the tumultuous circumstances Robinson bore that day and that season, nothing could ever fully capture the turmoil felt by Robinson himself.

Imagine, for a moment, stepping out on a Major League baseball diamond for the first time. Your spouse sits in the stands, perhaps alongside a small group of other friends and family. Aside from them and your teammates, most people in that stadium have never seen or met you before. In spite of this, you brace yourself against the inevitable slings and arrows of abuse you inevitably know to expect, because to some people, your physical appearance means more than the years of hard work and the uncanny ability you have shown on the field.

Newspapers have written about you, scrutinizing your abilities, your resolve, your motivations. You have made headlines in the past, being arrested for refusing to move to the back of a bus. Your temper, short and explosive, has created a reputation that precedes your person.

Your heart pounds violently as your cleats puncture the grass of the infield. Internally, your emotions vacillate between stubborn pride and a vague sense of fear and foreboding that you attempt to ignore. You try to keep your steps light, in spite of the heaviness of the burden on your shoulders and the weight of thousands of eyes staring directly at you. You make an effort to clear your mind and allow your baseball instincts to take over your actions, but you cannot disregard the staggering pressure to perform.

Jackie Robinson not only overcame this pressure, he did so in a way that, sixty-seven years later, we continue to remember and celebrate his influence upon the baseball world. In 1997, baseball commissioner Bud Selig mandated the retirement of number 42 across all of Major League Baseball. As a tribute to Robinson, however, every player across all thirty Major League teams will wear 42 during today’s games.

Prior to this evening’s Yankees-Cubs match-up in New York, members of Robinson’s family, Bud Selig, and members of the Steinbrenner family are expected to attend festivities at Yankees Stadium. Fittingly, as part of the event, the Yankees plan to unveil a plaque honoring Nelson Mandela, the late South African president who stood against apartheid.

In addition to the main event in the Bronx, teams across baseball will have their own methods for celebrating Robinson’s legacy. In Minnesota, for example, the Twins have dubbed this Celebrate Diversity Day. In Chicago, the White Sox will host a panel titled “Jackie Robinson: A Catalyst for Change in American Society,” in which White Sox chairman Jerry Reinsdorf, executive vice president Kenny Williams, Reverend Jesse Jackson, and historian Carol Adams will present their views on Robinson’s impact. And these are just a handful out of many examples.

At the end of the day, however, all of our tributes and celebrations will never provide us with the perspective to fully comprehend and appreciate what Robinson, himself, experienced in 1947. That experience will forever stay with Robinson alone. No doubt, his legacy remains more than deserving of all the honors we bestow upon his memory, but until the end of baseball history, there can only ever be one Jackie Robinson.