The concept of the Tao (the Way) has profoundly impacted world culture, most notably through the many translations of the Tao Te Ching and the Chuang Tzu. Its impact on ancient China was foundational, in the sense that it gave rise to Taoist religion, spirituality, cosmology, theory of statecraft and war, social relationships, painting, poetry, medicine and alchemy. Moreover, Taoism became interwoven with Buddhism from India, giving birth to Chan Buddhism (later known as Zen when transplanted to Japan). It is also closely associated with the I Ching (Book of Changes).
What has most fascinated me about Taoist thought, though, are its roots in mysticism and efforts to establish a protocol whereby practitioners might experience the personal awakening often referred to as enlightenment. This is a tradition that can be traced back to Taoism's earliest written text, the Nei-yeh (Inward Training), which was produced well before the more famous Tao Te Ching and Chuang Tzu.
The Tao, as the Way, may be best conceived of as the Way of Nature. Practitioners are encouraged to increase their sensitivity to the more subtle forces both within their environment and themselves (for example, through feng shui and t'ai chi, respectively). This recognition of the similarity of forces at work externally and internally proves instrumental in providing a first-hand experience of the unity of subject and object, which forms the very basis of the mystical experience.
This particularly shows up in the Taoist appreciation of naturalness. When turned outward, this appreciation produced some of the most sublime art and poetry based on a spontaneous identification with the places and seasons of nature. When turned inward, on the other hand, naturalness was used to make practitioners aware of their own original nature that exists prior to any familial or cultural conditioning. This inward training forms the basis of Taoist mind-body-spirit exercises aimed at returning the practitioner to the natural state of enlightenment.