When yoga becomes a vain search after a phantasmagoria…
The Yoga-sutra also prescribes meditation on Vishnu, and not meditation on the void. The so-called yogis who meditate on something other than the Vishnu form simply waste their time in a vain search after some phantasmagoria.
We have to be Krishna conscious—devoted to the Personality of Godhead. This is the aim of the real yoga.
Bhagavad-gita 2.61 purport