language group had started to lead to much speculation about the relationship between Greco-Roman cultures and those of more ancient peoples. In particular the Vedic culture of India was thought to have been the ancestor of European Classical cultures. Scholars sought to compare the genetically related European and Asian languages to reconstruct the earliest form of the root-language. The Vedic language, Sanskrit, was thought to be the oldest of the IE languages. Müller devoted himself to the study of this language, becoming one of the major Sanskrit scholars of his day. He believed that the earliest documents of Vedic culture should be studied to provide the key to the development of pagan European religions, and of religious belief in general. To this end, Müller sought to understand the most ancient of Vedic scriptures, the Rig-Veda. Müller translated the Rigveda Samhita book written by the 14th century Sanskrit scholar Sayanacharya from Sanskrit to English. Müller was greatly impressed by Ramakrishna Paramhansa, his contemporary and proponent of Vedantic philosophy, and wrote several essays and books about him. For Müller, the study of the language had to relate to the study of the culture in which it had been used. He came to the view that the development of languages should be tied to that of belief-systems. At that time the Vedic scriptures were little-known in the West, though there was increasing interest in the philosophy of the Upanishads. Müller believed that the sophisticated Upanishadic philosophy could be linked to the primitive henotheism of early Vedic Brahmanism from which it evolved. He had to travel to London to look at documents held in the collection of the British East India Company. While there he persuaded the company to allow him to undertake a critical edition of the Rig-Veda, a task he pursued over many years (1849–1874). He completed the critical edition for which he is most remembered. For Müller, the culture of the Vedic peoples represented a form of nature worship, an idea clearly influenced by Romanticism. Müller shared many of the ideas associated with Romanticism, which coloured his account of ancient religions, in particular his emphasis on the formative influence on early religion of emotional communion with natural forces. He saw the gods of the Rig-Veda as active forces of nature, only partly personified as imagined supernatural persons. From this claim Müller derived his theory that mythology is "a disease of language".