The desert has given mankind some of its greatest prophets. Out of its solitude there appeared a wild-looking man, dressed in a rough camel's hair girdle. He came living on locusts and wild honey, but fasting often. He went among the cities of Judea, praying, calling for repentance, denouncing wickedness, and proclaiming the Coming. This man was John the Baptist.
Immediately after illumination came to him on the road to Damascus, Saul went to the desert. He stayed for three years, engaged in self-training and inner development. When he emerged from it, he was Paul the Initiate.
Islam was born in the desert wastes of Arabia.
It was not for nothing that the early Christian mystics of lower Egypt fled from populous cities to the open spaces of the desert. Their instinct was right.
-- Notebooks Category 3: Relax and Retreat > Chapter 5 : Solitude > # 34