Kun is one of the eight trigrams (bagua) of the Yijing. It is composed of three broken yin lines, and its attribute is Earth, the Receptive, the pure yin principle of yielding, nourishing, and sustaining, the ground that receives and gives form to what the Creative begins. In the family symbolism it is the Mother, and its polarity is yin. Its associated element is Earth, and in the Later Heaven arrangement of the bagua its direction is southwest, though in the Earlier Heaven arrangement it stands due north at the bottom. Each of the eight trigrams combines with another to form the sixty-four hexagrams of the Yijing. These are the conventions of the Chinese cosmological and divinatory tradition, in which Kun, all yin, is the counterpart and complement of the all-yang Qian.
Kun's Fu Xi position at due north, opposite Qian at due south, gave the pure yin trigram a further afterlife outside Chinese cosmology. In 1701 the Jesuit missionary Joachim Bouvet sent Gottfried Wilhelm Leibniz, from Beijing, a diagram of the Fu Xi ordering of the sixty-four hexagrams; Leibniz, already developing binary arithmetic, recognised that Kun's three broken lines and Qian's three unbroken ones mapped onto his own 0 and 1, and in a paper published in Paris in 1703 he noted, in his own words, that Fu Xi appeared to have anticipated his binary system some four thousand years earlier, all yin and all yang standing at the two poles of the same numerical idea.
Sources Fathoming the Cosmos and Ordering the World: The Yijing (I Ching, or Classic of Changes) and Its Evolution in ChinaRichard J. Smith with The I Ching, or Book of ChangesRichard Wilhelm (trans.); Cary F. Baynes (English trans.), The Five "Confucian" ClassicsMichael Nylan