As this Upanishad opens with the word ?Isa?, this is titles as Isavasya Upanishad. Part of Yajurveda, this is the smallest one with only 18 verses. This preaches the ?Isa Vidya? or search for the ultimate beyond the light. To help the reader, these 18 verses are presented in seven small chapters; each verse appears in devanagari, transliteration in tamil , word for word meaning, a summary and lucid explanation as per Sri Sankara?s commentary and discussions by Senior Swami?s of Sri Ramakrishna order published earlier as book/article/editorial. Explanation in tamil of Isavasya Upanishadam is provided by Swami Asutoshananda.