Fifteen Portals to the Supreme Meditation Techniques from Aparoksanubhuti
by Swamini Vimalananda Saraswati

The mother bird flies to the top of the tree to eat the sweet, ripe fruit.  The baby bird, not having strong wings, takes smaller flights to reach the same. 

This simple and effective book on Meditation Techniques, commented upon by Swamini Vimalananda, describes both the straight flight of Raja Yoga or Vedantic Meditation and the preparatory steps of Hatha Yoga (popularly known as Yoga).  the thought provoking ideas and practical tips on meditation make it easy to open the Portals to the Supreme.