Short answers, pulled from the story.
Christian mysticism is the heart of the tradition defining the preparation, consciousness, and transformative effect of a direct presence of God. Until the sixth century, this practice was called theoria, a Greek term meaning to look at, gaze at, or be aware of the divine.
The Desert Fathers and Mothers were early monks and nuns who withdrew to the deserts of Sketes in the fourth century to live lives of austere simplicity. They practiced continuous meditation on scripture to fight demons and gain liberation from bodily passions while seeking unceasing prayer.
John of the Cross described the dark night of the soul as a period of final and complete purification marked by confusion, helplessness, and a sense of the withdrawal of God's presence. This stage is a necessary process of unselfing where the individual renounces everything that might become an obstacle between the soul and God.
Teresa of Avila used the metaphors of watering a garden and walking through the rooms of a castle to explain how meditation leads to union with God. She distinguished nine grades of prayer ranging from vocal prayer to the prayer of transforming union where the soul is permanently established on a transcendental level.
Gregory Palamas taught that God is transcendent in essence but immanent in energies, arguing that the uncreated light seen by the apostles on Mount Tabor is the same light experienced in contemplative prayer. The Council of Constantinople affirmed his teachings on the 1341 and condemned the views of Barlaam of Calabria.
Miguel de Molinos was convicted of moral enormities and heretical doctrines and made a public profession of his errors on the 3rd of September 1687. He was sentenced to imprisonment for life where he died in 1696 or 1697 after his views were attacked by the Jesuit preacher Paolo Segneri in 1681.