Supreme Court Justice Clarence Thomas warned of the threat progressivism poses to the United States and its founding principles during a speech about the 250th anniversary of the Declaration of Independence.

Thomas addressed a crowd on Wednesday at the University of Texas at Austin, where he discussed the semiquincentennial on July 4, in a roughly 50-minute speech. He warned that it is “unclear” if the founding principles of limited government and individual rights will endure, pointing to the rise of progressivism, which began during Woodrow Wilson’s presidency in the 1910s.