In Germany and Italy, the Fascist governments took a keen interest in organising such journeys.
As in most such journeys, the best explanation is personal.
I present several formulae as well as concrete numbers that can be used to help determine populations that could survive such journeys in good health.
Population genetics theory, calculations and computer modeling determine that a properly screened and age- and sex-structured total founding population (Nc) of anywhere from roughly 14,000 to 44,000 people would be sufficient to survive such journeys in good health.
Britain's leading coach operator said there would be 1m fewer journeys in the first full year since the government cut the grant which gave over-60s and disabled people half-price travel, out of 2.9m such journeys in 2011.
Mr. Advani rose to prominence by making such journeys in the 1980s and '90s, but his decision raised questions whether there would be another battle for leadership at the top of the BJP.
Though polar bears are adept swimmers, they are not built to swim long distances, and they were rarely seen making such journeys in earlier decades.
An essay on the visio of Tundal by Cavagna has an interesting account of the changing nature of such journeys in the literature, which shows very clearly, for instance, that the idea of purgatory was thoroughly alive in the vision of Drithelm.
The start in any such journey is the courage to be honest.
