E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Initiates who have proved their courage and purity by passing through sundry tests and trials. It is a Hindu word applied to certain Buddhists. They are also called Masters. According to Theosophists, man has a physical, an intellectual, and a spiritual nature, and a Mahâtma is a person who has reached perfection in each of these three natures. As his knowledge is perfect, he can produce effects which, to the less learned, appear miraculous. Thus, before the telegraph and telephone were invented it would have appeared miraculous to possess such powers; no supernatural power, however, is required, but only a more extensive knowledge.
Mahâtma is a well-known Sanskrit word applied to men who have retired from the world, who, by means of a long ascetic discipline, have subdued the passions of the flesh, and gained a reputation for sanctity and knowledge. That these men are able to perform most startling feats, and to suffer the most terrible tortures, is perfectly true.Max Muller: Nineteenth Century, May, 1893, p. 775.