Mysticism is an innate human query to realize the truth behind all existence. The great mystic, excelsior homme d' esprit Wordsworth was an optimistic pantheist and nature was his benign God. Furthermore, Clarum'et venerabile poet Emerson was an occidental who imbibed orientalism transcendentally. Nobel Laureate Tagore was a versatile poet-philosopher - dramatist-actor-painter and a humanist at large. After comparing and analyzing all their important works and contemplating on the vast criticism on them this book has come into existence. Moreover, like an are-en-ciel (rainbow) it reflects all the aspects, characteristics and types of mysticism including Eastern, Western and its history in English poetry. This book is functional for all the students doing graduation, or any post graduation course in English Literature or research works on any of these three poets or on mysticism. People who are interested in spirituality, philosophy, nature poetry, religion or cosmic consciousness would find this work quite elevating and informative a' tout force. Hope it will carry the readers to the mystic's illumined ecstatic world of light, knowledge and creativity ad infinitum.