The question for the Supreme Court in an argument today was whether a state may make it a crime to burn a cross without at the same time trampling on the protection that the First Amendment gives to symbolic expression. The case, concerning a 50-year-old Virginia law, raised tricky questions of First Amendment doctrine, and it was not clear how the court was inclined to decide it -- until Justice Clarence Thomas spoke.

A burning cross is indeed highly symbolic, Justice Thomas said, but only of something that deserves no constitutional protection: the ''reign of terror'' visited on black communities by the Ku Klux Klan for nearly 100 years before Virginia passed the law, which the Virginia Supreme Court declared unconstitutional a year ago.

A burning cross is ''unlike any symbol in our society,'' Justice Thomas said.

''There's no other purpose to the cross, no communication, no particular message,'' he continued. ''It was intended to cause fear and to terrorize a population.''

During the brief minute or two that Justice Thomas spoke, about halfway through the hourlong argument session, the other justices gave him rapt attention. Afterward, the court's mood appeared to have changed. While the justices had earlier appeared somewhat doubtful of the Virginia statute's constitutionality, they now seemed quite convinced that they could uphold it as consistent with the First Amendment.