The 8 Chinese trigrams (and central number 5 which does not have a Trigram), are associated with a cardinal direction, number, element, organ, body part, illness and other associations. These Trigrams are rooted in the I Ching (Book of Changes) and when two of the trigrams are combined, they become 64 hexagrams. In Classical Feng Shui, there are 8 compass directions and the Tai Chi (middle sector). This creates up an octagonal shape that can be laid over a plot or floor plan (known as the Bagua).