Vitrivius - Source for Roman architecture in Ceasar's times. De Architectura Libri X - his ten books (chapters) on architecture.Wonderful site written in Latin with English translation.
During the later 1920s and 1930s Wright's Organic style had fully matured with the design of Graycliff, Fallingwater and Taliesin West.
In Chinese philosophy, the concept of yin yang ([yin – simplified Chinese; traditional Chinese: [pinyin] [yang - simplified Chinese] ; traditional Chinese: [pinyin: yáng] sometimes referred to in the west as yin and yang) is used to describe how polar or seemingly contrary forces are interconnected and interdependent in the natural world, and how they give rise to each other in turn. The concept lies at the origins of many branches of classical Chinese science and philosophy, as well as being a primary guideline of traditional Chinese medicine, and a central principle of different forms of Chinese martial arts and exercise, such as baguazhang, taijiquan (tai chi), and qigong (Chi Kung) and of I Ching divination. Many natural dualities — e.g. dark and light, female and male, low and high, cold and hot — are thought of as manifestations of yin and yang (respectively).
This then is my view on how to achieve designs that fall in the category of "simplicity", that is, designs of systems that can be understood by the relevant audience(s), and additional audiences, if needed.
Much of my interpretation is derived from the philosophies or religions on Taoism that were composed by Lao Tse or Lao Tzu.