The Origin of Taijiquan
Taijiquan, according to one legend, was developed by a Taoist immortal (the Buddhist equivalent would be one who has achieved nirvanna) by the name of Chang San-feng (alternatively, Zhang Sanfeng ) who was inspired to develop this internal wushu discipline while witnessing a duel between a cobra and an eagle. Chang San-feng was impressed by the defensive tactics deployed by the snake (had the cobra attempted to flee it would have been paralyzingly wounded by the eagle's piercing peck, then strangled to death in the clutch of the eagle's powerful claws). By controlling its fear and maintaining total concentration on the eagle's various lunges and retreats, the cobra managed not only to avoid being hit by the eagle's deadly pecks, but itself managed to deliver a fatal blow to the eagle's neck, killing it.
Other theories concerning the origin of taijiquan hold that the discipline was developed over many centuries as a result of the painstaking work of many different kung fu ("hard-won achievement") masters, and as such represents a genuine synthesis of both the internal as well as the external form of kung fu wushu. Whichever explanation is the most likely (others may yet appear), the fact remains that although taiji quan, according to what is known of it via the historical record, first began to be formulated near the end of the 17th century, while it was first introduced as a complete, ready to be practiced discipline at the beginning of the 20th century.