When Rickey joined his young player, the coach found Thomas tugging at his hands lamenting, "Black skin . . . if I could only make 'em white."
Some think that this story, oft-told by Rickey, is apocryphal. But whether it is real or not, it speaks to Rickey's feelings on the matter of racial equality.
Now, as we approach the 60th anniversary of one of this country's most momentous historical events, when Jackie Robinson took the field for the Brooklyn Dodgers on opening day 1947, we should stop to remember that "baseball's great experiment" - as it has been termed by Jules Tygiel - was the product of a providential partnership.
On the one side stood Jackie and Rachel Robinson; on the other side was Branch Rickey.
Mr. Rickey, as he was called by virtually everyone that came in contact with him, is rightfully remembered as the architect of many elements of baseball, including the role of general manager, spring training, and the minor leagues.
Yet, his greatest contribution to the game arguably came that day in 1945 when the then-general manager and co-owner of the Brooklyn Dodgers signed Robinson.
As his recounting of Thomas and South Bend indicated, Rickey had a strong dislike of segregation, which was the unwritten rule of law in pro baseball.
The practice chilled him when he practiced at Sportsman's Park in St. Louis during his days with the Cardinals.
Blacks there were not allowed to sit in the grandstand with white fans. And of course not one black face appeared in a big-league uniform.
Rickey's disgust is well-documented.
"Ethnic prejudice has no place in sports, and baseball must recognize that truth if it is to maintain its stature as a national game," Rickey said.
Another Rickey observation was about the practical. "The greatest untapped reservoir of raw material in the history of our game is the black race," he said.
Whether his motives were about a sense of innate fairness or about making his team better - two motives that were clearly present - is less important than the fact that Rickey was committed to making integration happen. And whether or not Bill Veeck had truly intended to buy the bankrupt Philadelphia Phillies and stock them with Negro league players in 1943 - before commissioner Kenesaw Mountain Landis had the Phillies sold to another buyer, Rickey was the first baseball executive to seriously consider and pursue integration. And he did so alone.
In order to overcome decades of institutionalized segregation in the game, Rickey had to orchestrate a process that pretty much guaranteed success. The weight of a race would rest upon the shoulders of the individual selected as the pioneer, and that individual had to be up to the task, both in terms of ability to perform on the field and the ability to absorb the vitriol of fans and opposing players that was sure to come.
"The idea of a black breaking into baseball was going to be opposed broadly . . . so he took extreme precautions, planning on all sides," said Branch Rickey III, grandson of the barrier-breaking executive.
Through famous scouts such as Clyde Sukeforth and Tom Greenwade (who later discovered Mickey Mantle), Rickey carefully scouted the Negro leagues, under the guise of forming a team called the Brooklyn Brown Dodgers for the United States League, a new league for black players.
There were many outstanding Negro league players, including Satchel Paige, Josh Gibson and Monte Irvin. But Rickey found his man in Jackie Robinson, who had been a tremendous multi-sport athlete at UCLA and had recently served in the Army.
The pressure to integrate the major leagues built consistently during World War II, coming from the black press, especially Wendell Smith, Sam Lacy and Joe Bostic, and from interest groups who pointed to the enormous injustice of black Americans fighting and dying during the war, yet being restricted from baseball.
By late 1945, with the war over and the troops coming home, Rickey felt the time was finally right. That October he announced the signing of the first African-American baseball player since Moses Fleetwood Walker in 1884.
Knowing that it would be frightful to let Robinson play minor-league ball in the Jim Crow South, Rickey mapped out Robinson's path to Brooklyn through Montreal, home to the Royals, the Dodgers' AAA club in the International League.
After a very difficult spring training in segregated Florida in 1946 with the Royals, Rickey moved his spring-training camp in 1947 to Cuba, a land where there was complete mixing of the races.
Then in 1948, Rickey took an abandoned naval air station in Vero Beach, Fla., and created Dodgertown, a place that was at least somewhat insulated from the oppressive segregation that characterized the deep South.
"Jackie carried it out on the field. My grandfather, to some degree, covered his back," said Branch Rickey III.
Stanley "Doc" Glenn, a former Negro leaguer with the Philadelphia Stars and currently president of the Negro League Players Association, recently said during a presentation at St. Joseph's University, "Baseball has done more for America than the Supreme Court."
What Mr. Glenn could have added was that Branch Rickey also did more for America than the Supreme Court.
In an era in which it would have been much more comfortable to simply accept the status quo, Branch Rickey had the courage, the foresight and the intestinal fortitude to push for radical change - 20 years before the nation followed their lead with the landmark civil-rights legislation of the 1960s.
Branch Rickey and Jackie Robinson changed the face of baseball, and for that, all of us owe these men and their special partnership a significant debt.
John B. Lord is professor of marketing at St. Joseph's University, where he teaches a course called "Baseball: Tradition and Business." He recently worked with Bill Giles on the Phillies chairman's memoirs, published this spring. He can be contacted at firstname.lastname@example.org.