The Three Pure Ones are the highest Deities in Taoism. “The Three Pure Ones” transcend the entire hierarchy of Taoist deities. In the middle is the ultimate highest deity of Taoism, the Primordial Heavenly Worthy. To your right is the Spiritual Treasure Heavenly Worthy, and to your left is the Supreme Way Heavenly Worthy.  

“The Three Pure Ones” is the avatar of Taoism. AVATAR is a word that is commonly heard but rarely understood. In English, the word has come to mean “an embodiment, a bodily manifestation of the Divine.” The void or great emptiness, in the beginning, is called “Wu Chi”, or primordial chaos, at this state the Tao is a dispersed form or “Chi” when reunited it is transformed into a divine being. This divine being is Tai Shang Lao Zun or Supreme Patriarch Lao Zi.
He then transforms the “One” which is Primordial Heavenly Worthy or Reverend Yuan Shi of Yu Qing. He holds a flaming divine pearl which represents the creation of the Universe, however, at this stage, the Universe is in a chaotic stage.

Eventually, later he forms another divine being, Spiritual Heavenly Worthy or Reverend Ling Bao of Shang Qing. At this point of time, there are two forces called the “Yin” and “Yang” represented as “Tai Chi” myriads things can be formed by these forces. Therefore Spiritual Heavenly Worthy or Reverend Ling Bao of Shang Qing holds a “Ru Yi”, a wish-fulfilling ornament.
Finally, when all things are created Tai Shang Lao Zun descend and sits on the right, he holds a mystical fan, symbolizing the completion of the Universe, and the way of Tao can be spread, and living beings can seek salvation. 

Articles Source from Taoist Secret Website.