PMC

The I-Ching itemizes 64 combinatorics of Yin and Yang. Source: www.theory.org/~strthrwr/retired/iching.html.

The pentagram in Proto-cuneiform text from Jemdet Nasr (3000–2500 BC). Source: Englund RK et al. ().

The pentacle as a ubiquitous symbol of Neo-paganism (). Image used by permission of the publisher, Llewellyn Worldwide Ltd. www.llewellyn.com. All rights reserved.

Pythagorean pentagram from Heinrich Cornelius Agrippa's ‘Libri Tres de Occulta Philosophia’ with the word γιεια or Hygieia, Health, inscribed on its outer circle ().

Hopfield-style networks are used in the context of Systems Biology. Source: Institute for Systems Biology. www.systemsbiology.org. Reprinted with permission.

The golden ratio, or Phi (Φ) in the pentagram's geometry. Image based on a drawing by Steve Edwards of SPSU Math Department available at: www.spsu.edu/math/edwards/main.html. Drawing used with permission.

The concept map of the healthy Sheng and Ke cycles. Lines in the opposite direction form the unhealthy Cheng and Wu cycles. Source: Al Stone, Lung Cancer and Five Elements. www.acupuncture.com. Reprinted with permission.