Between February and April of 1968, The Beatles embarked on a transcendental meditation retreat and course with Maharishi Mahesh Yogi in Rishikesh, India. During their spiritual respite, the songs of their ninth album, The Beatles (the White Album), started taking form. John Lennon and Paul McCartney would often meet secretly to write in between meditative breaks, while George Harrison, who had been squeezing in typically two or more of his own songs on prior Beatles records, was also becoming a more prolific songwriter—even writing for other artists—as well as a musician, during this time.
Source: americansongwriter.com