Ronald Stuard Thomas was a Welsh priest and poet. Throughout his life, genuinely he believed that his double vocation was compatible. For about forty-two years, he had worked as an Anglican priest in the rural parishes of Wales, but his writing poetry had lasted over fifty years. From his early years of life, passionately he loved the natural beauty of Wales. His early poetry emerges from such a passionate, romantic love with the world of nature in Wales. However, as the years pass, his poetry undergoes changes of its ideas and techniques when he moves around the remote northern part of Wales to minister his parishes which exerts a profound influence on his poetry. After his encounter with the hill farmers in Manafon where he worked for over twelve years from 1942, his earlier romantic idea of Welsh nature gives way to the harsh reality in which the prototypical figure of the hill farmer, Iago Prytherch, struggles to survive with endurance. Thomas was strongly against scientific technology and the machine. He found an enemy to the natural world in a greedy mind craving for commercial profits through the machine which is de-humanizing as well as insulating man from natural processes. He believed that science and technology bring about a divorce of poetry from the natural world. He also believed that the development of technology breaks not only the silence of the countryside but also destroys the beauty of the natural world. For him, silence is only the medium of God whose messages are delivered to man by the world of nature. Man in the modernized world cannot have a direct contact with God. Only through the wild world of nature, he believed that man can have a revelation of God while accepting the fundamental fact of God``s existence, a mystery in whose presence one can only rest in one`s faith and silence. At best, the poetry of Thomas could be called that of a nature mystic who had an immediate contact with the ultimate reality in and through nature.