It is pretty clear that they are ineffective in stopping the course of thought at present, but they have not always been so in the past and we cannot be sure that they will not be so in the future.

Political activism
Arriving in Cambridge as a Catholic Bernal became a socialist as a result of a long night arguing with a friend. (1965). 0143.

John Desmond Bernal[pronunciation?]FRS (10 May 1901 – 15 September 1971) was one of the United Kingdom's most well-known and controversial scientists.