The president of Russia, Vladimir V. Putin, once described the collapse of the Soviet Union as a “geopolitical catastrophe.” But the political thinker who today has the most influence on Mr. Putin’s Russia is not Vladimir Lenin, the founder of the Communist system, but rather Ivan Ilyin, a prophet of Russian fascism.

The brilliant political philosopher has been dead for more than 60 years, but his ideas have found new life in post-Soviet Russia. After 1991, his books were republished with long print runs. President Putin began to cite him in his annual speech to the Federal Assembly, the Russian equivalent of the State of the Union address.

To complete the rehabilitation, Mr. Putin saw to it that Ilyin’s corpse was repatriated from Switzerland, and that his archive was returned from Michigan. The Russian president has been seen laying flowers on Ilyin’s Moscow grave. And Mr. Putin is not the only disciple of Ilyin among the Kremlin elite.

Vladislav Y. Surkov, Moscow’s arch-propagandist, also sees Ilyin as an authority. Prime Minister Dmitri A. Medvedev, who served as president between 2008 and 2012, recommends Ilyin to Russian students. Ilyin figures in the speeches of the foreign minister, the head of the constitutional court and the patriarch of the Orthodox Church.

What are the ideas that have inspired such esteem? ...