In Greek the verb 'tithenai' means to put or to place and the Latin 'thesauros' meaning treasure (also in the Albanian Language). However it was Roget who used it to mean 'collection of words arranged according to sense' in his original edition published in 1852.
His wasn't the first however as Philo of Byblos authored the first script that could now be called a thesuarus and in the 4th century a verse form was written in Sanskrit, the Amarakosha.
Peter Mark Roget collected words and phrases in a simple notebook to assist him in his work as a writer and lecturer. He then spent four years of his retirement expanding and systemizing this material, the purpose being 'to facilitate the expression of ideas and assist in literary composition.' Still, not everyone recognized the purpose of the work and reactions were mixed as to how exactly it could be used. One reviewer did say that it would one day rank as important as Samuel Johnson's Dictionary and that prophesy has certainly come true with over 30 million copies sold and is one of the best-loved reference books in English. Possession of the book has been used as a mark of good character - J.M. Barrie described Captain Hook in Peter Pan as 'The man is not wholly evil - he has a Thesaurus in his cabin.'
The book is now not only used to assist people with their writing as, over the past century, a new market has developed, the crossword puzzle - the New York Times naming Roget as the 'Saint of Crosswordia'.
Not very many changes have taken place within the structure of the book since its inception. the layout was in columns but now entries are in units as these are easier to follow. The vocabulary content has increased hugely as few entries have been deleted since Roget's edition. Some rare or archaic words have been dropped but the advances in both science and society mean that new words have come into common usage, especially those connected with computing and the Internet, as well as beauty treatments, biotechnology, tourism, lifestyle, climate changes, etc. In the up-to-date editions there are sections on literary quotations and text boxes.
The thesaurus must keep up with all the latest developments and has stood the test of time for a publication begun almost two hundred years ago by a man who had worked with Dr Beddoes and his laughing gas experiments, working with Jeremy Bentham and being influenced by his Utilitarianism ideas. He went on the Grand Tour and got trapped in Geneva when the Peace of Amiens collapsed. He was a qualified doctor working in both Manchester and London, being elected as a member of the prestigious Royal Society. He set up the Northern Dispensary charity and gave lectures to medical and science students as well as being one of the doctors involved in the Millbank prison epidemic investigation. He read voraciously in several languages, was married with two children and wrote for the Encyclopedia Britannica. Science and mathematics remained his true interests and he was Fullerian Professor of Physiology, lecturing at the Russell Institution for thirty years. His Bridgewater Treatise prepared him for the work of creating the Thesaurus as he had set out Natural History in all its variety as well as assisting with the classification of the Medical and Chirugical Society and Royal Society libraries. He loved organizing knowledge and for that we are truly grateful.