The separation he was speaking about was between pure awareness (what is known as the Self) and our identification with it (Mind, or what mind does).
Even when he talked about the yogi superpowers that the practice may bring along he said they are all to be avoided except for 3.36, which is focusing all of our attention on this very distinction, what is real and what is not, because this super power is what brings us to unveil reality, see behind the curtain, notice there is no wizard and rather that we were all there all along all together.
“Most people know that the word yoga means union… but Patanjali refers to yoga as a process of separation. How can this contradiction be explained?… Can be explained by the Samkhya philosophy which is the basis of the yoga sutras“
Fortunately today I come across a clarification paragraph (from Satyananda’s “Four Chapters on Freedom“) that explains the point of: Is it union? Or, is it separation? Or is it both?
In Patanjali’s yoga (Following the Yoga Sutras), we start with separation to reach union. We go from the gross to the subtle, from the darkness to the light.
“Samkhya divides existence and individual being into two aspects… the Seer and the Seen…. practice of yoga is concerned with Viyoga, separating awareness and the mind-body… “
that can only be experienced by experience and the writer warns that no amount of reading will ever convince anyone, then
“First the seer and the seen are separated and when this is achieved they are perceived to be the same”
So separation leading to union.
Now I see. Let’s practice to experience.