In spring 1957, two weeks before the opening of Henry Purcell’s opera “Dido and Aeneas” at the University of Texas at Austin, Barbara Smith, a 19-year-old mezzo-soprano, received some bad news. She would not be appearing as Dido, a role she had been rehearsing for months.

Ms. Smith was black. The singer cast as Aeneas was white. In the South, then emerging only slowly from strict segregation, this was a problem, even though the two principal characters do not kiss, embrace or even touch.

Joe Chapman, a Democrat in the State Legislature from Ms. Smith’s own district in the pine country of Northeast Texas, had taken the matter up with Logan Wilson, the university’s president. During their conversation, Mr. Chapman had told him that the opera’s casting might be bad publicity for the school, especially since the Legislature was preparing to vote on an appropriations bill.

Three days before the opera was scheduled to open, The Houston Post broke the story, under the headline “Negro Girl Out of UT Opera Cast.” The Daily Texan, the student newspaper, followed with an article the next day. Its reporter asked Mr. Chapman, a former Texas railroad commissioner, if he believed that the Legislature had the right to dictate policy to the university.