Milarepa was a murderer who turned to buddhism and became a student of the great sage Marpa the translator. Milarepa's father died when Milarepa was seven and he was placed under the care of his aunt and uncle.
His uncle and aunt stole his parents' fortune so, on the advice of his mother, Milarepa started practicing bon sorcery and killed them. Remorse for his actions caused Milarepa to seek out a teacher.
Marpa had him build a stone tower. It was an enormous task and when it was finished Marpa had it destroyed. This happened again and again, three times. Milarepa almost went mad in the endeavor. Finally he built a tower at Lhodrag, which was allowed to stand, it still exists today.
Marpa explained that Milarepa was burning off negative karma. This process was intended “to purify the negativity of his past actions, so that Milarepa could begin his studies with fewer obstacles.”
He was sent to mountain caves to meditate for years at a time and learned many tantric yoga techniques. Milarepa became a bona fide buddha, transitioning from murder to enlightenment in a single lifetime. Milarepa was a famous singer and poet and was said to have written over a hundred thousand songs.
Many other tantric yogis were also confined in their training to cells and caves including the wonderful teacher Chogyam Trungpa Rinpoche (1939-1987) who talks about it in his excellent book, The Myth of Freedom.
So maybe this strange time will give us all an opportunity to work on our stuff. Peace. Towards enlightenment.