Philby the Masterspy: Soviet triple agent

Kim Philby, a former British Secret Intelligence Service officer and an agent for the Soviet Union at the same time, was perhaps the most famous of a group of British government officials who served as Russian spies from the 1930s to 1950s.

Philby came from a very respected background in British society and attended Trinity College at Cambridge University. His life seemed to be quite predictable and clear. What made him turn to spying for the USSR? Source