This section is from the book "Holistic Medicine", by Shriniwas J. Kashalikar.
Pratyahara means withdrawal of senses, dharana means fixation of mind on any object, dhyana means meditation or one pointedness of mind Samadhi means self realisation.
These four headings do not seem to represent separate stages however, Pratyahara associated with capacity to transcend all material temptations representing cruder energy' dharana associated with focusing of the total being on the supreme reality, and samadhi associated with total sublimation of the individual or total merger of the individual consciousness with cosmic consciousness.
The study of these states required bold and modern concepts, sophisticated gadgeOy and dedication to the subject with individual practice and introspection.
The foregoing is a glimpse of YOGA, as can be sensed today. It is clear that it does not confine to today's scientific knowledge alone or today's perception of yoga practitioners as found in their writings,), or the texts of yoga It leaves us at the edge of infinity because YOGA is a process of infinitesimal enlightenment and voyage to the supreme cosmic strength.