In alchemy, nigredo, or blackness, means putrefaction or decomposition. Many alchemists believed that as a first step in the pathway to the philosopher's stone, all alchemical ingredients had to be cleansed and cooked extensively to a uniform black matter.
In analytical psychology, the term became a metaphor for "the dark night of the soul, when an individual confronts the shadow within."
St. John of the Cross OCD (Spanish: Juan de la Cruz; Latin: Ioannes a Cruce; né Juan de Yepes y Álvarez; 24 June 1542 – 14 December 1591) was a Spanish Roman Catholic priest, mystic, and Carmelite friar of Converso ancestry. He is a major figure of the Counter-Reformation in Spain, and he is one of the 38 Doctors of the Church.
John of the Cross is known for his writings. He was mentored by and corresponded with the older Carmelite nun Teresa of Ávila. Both his poetry and his studies on the development of the soul, particularly his Noche Obscura, are considered the summit of mystical Christian literature and among the greatest works of all Spanish literature. He was canonized by Pope Benedict XIII in 1726. In 1926, he was declared a Doctor of the Church by Pope Pius XI, and is also known as the "mystical doctor".