Southwest, a bearing of 225 degrees, holds the trigram Kun, the receptive, earth, the pure yin principle, in the Later Heaven arrangement, and it is associated in Chinese practice with the mother, with nourishment and with yielding strength. In Hindu Vastu the southwest is Nairitya, and it is the quarter given the greatest weight and mass in a building: the master bedroom, the heaviest walls and the highest point of the structure are placed there, and it is kept closed rather than open, the exact inverse of the treatment of the northeast. The two rules together produce the characteristic Vastu building that is heavy and high to the southwest and light and open to the northeast, sloping down toward the northeast corner. Whatever one makes of the cosmology, the resulting form is a coherent architectural discipline with its own logic.
In Hindu Vastu Shastra, the dikpala of the southwest is Nirṛti, a goddess or, in some texts, a rakshasa associated with destruction, decay and misfortune, and the quarter is treated as the least auspicious of the eight, generally reserved for storage, heavy furniture or the master bedroom under the reasoning that its stabilising weight anchors the household against the direction's own instability, but avoided for entrances or for the kitchen. In Chinese Bagua cosmology, the corresponding trigram is Kun, the Earth, carrying the Earth phase and associated in Feng Shui applied to interior space with relationships and marriage, a considerably more favourable reading than Vastu's own treatment of the same quarter, illustrating again how little directional symbolism transfers between unrelated traditions.