Chapter 684

Soul Formation was split into three substages. There was the first Dao Discovery Realm, the second Dao Infusion Realm, and the final Dao Perfection Realm. 

The key to cultivating an Origin Soul was that it now had sufficient spirituality and could freely roam the world, but the use of spirit energy to fortify it is minimal, and merging your soul with the energy was not enough to induce a qualitative change. 

So one had to let their soul out of their body and let it cultivate directly, abandoning not the energy of the world, but the truth of it. In other words, Soul Formation is the realm of cultivation where a cultivator first comes into contact with the illusory 'Dao'.