This commentary expresses the ideas of Sri Babaji, the master kriya yogin who can be reached in the astral world in a sunlight body in the dimension known as Siddhaloka. This was inspired to the writer by him. Kriya yoga which was defined by Sri Patañjali, is divulged freely in the Gita.
The practice with its secretive techniques which are only known to a few persons and their confidential disciples, is fully sketched by Lord Krishna.
Undoubtedly one requires instruction from an expert, but the instructor does not have to be physically present. And most of all, the outline of the practice is given freely in the Bhagavad-Gita by none other than Sri Krishna, the ultimate yogin.