I found this quote on a website when searching online:

"C.G. Jung's described the coniunctio oppositorum, or union of opposites, as the goal of individuation. Jung noted that the mysterium coniunctio, the relationship between yin and yang, can be true or false (Ref 7). Jung did not hold to a Biblical view of evil, but he certainly struggled with evil as a reality in human affairs. In his own way, Jung attempted to understand how we all must come to terms with the masculine and feminine principles in life, and in God Himself, in order to be whole persons, whether we are single or whether we are married. The above woodcut, illustrative of Jungian thought, is from a medieval book, Rosarium Philosophorum Alchemiae de Lapide Philosophica, 1550. Jolande Jacobi in her book, The Psychology of C.G. Jung, (Yale University Press, London, New Haven, 1973) comments on this diagram as follows:

The alchemical conception of one of the stages of the coniunctio. Here the 'king' and the 'queen,' who may be taken as Sol and his sister Luna, appear as symbols of the primordial psychic opposites, masculine and feminine. Their 'marriage' is meant primarily in the spiritual sense, as is clear not only by the words of the middle band spiritus est qui vivificat, but also by the dove as symbol of the spirit, and according to the ancients, amor coniugalis. The primordial opposites confront one another in their naked, unfalsified truth and essence, without conventional covering; the difference between them is evident and 'essential;' it can be bridged in fruitful union only through the intermediary of the spirit symbol, the dove, the 'unifier' which intervenes from 'above.' The branches held to form the cross, the flores mercurii, and the flower hanging down from the dove's beak---all these symbols of the process of growth illustrate the common effort of man and woman in the living work of the coniunctio."

source: http://ldolphin.org/YinYang.shtml