After a century significantly « return »:

• SOCIAL CHANGES have no lesser importance. Protagonist was the Bolshevik Revolution of 1917. The most extreme of social revolutions aimed at unhinging the world order at the time.
  After a century they significantly “recur”
• SCIENCE (the confirmation of A. Einstein’s theory of gravitational waves for the first time in the history of mankind opens up the possibility of realizing the first space-time journey of man into the Cosmos),
• ART (the rediscovery of Malevich and how much “suprematism” is present around us; as in the work of Zaha Hadid, recently deceased, Lazar Khidekel architect-environmentalist ante-litteram of the early twentieth century as singers of a spatial suprematist architecture projected in the 21st century; other fields of research are influenced by the avant-gards and Malevic, as in music, video art , digital art etc.)
• SOCIAL CHANGES inherent in the ongoing globalization process of which the scope of mass migration, the scope of extreme climate change, the loss of biodiversity, the extent of pollution and senseless use of natural resources in the environment constitute a significant aspect.
  

Two other long-term structural processes contribute to increasing uncertainties and fears but also to expectations : the acceleration in the exploration of the Cosmos and the first observation of a gravitational wave signal occurred on September 14, 2015 ( in my opinion, the start date of the Cosmic and Digital Era and the end of the modern and contemporary Era), on the one hand, and the acceleration of technological progress and, in particular, Artificial Intelligence and robotics with the unfolding of the Digital Era, on the other.