MOHAN SIṄGH VAID, BHĀĪ, (1881-1936), apothecary, writer, collector of books and social reformer, was born at Tarn Tāran on Phāgun sudī 7, 1937 Bk/7 March 1881, the youngest of the four sons of Bhāī Jaimal Siṅgh (1843-1919), who too was a vaid (practitioner of Āyurveda or Indian system of medicine) of long standing. Mohan Siṅgh had no regular schooling after his preliminary education in the Gurmukhī Vidyālā at Tarn Tāran. He, however, studied books on Sikh religion and history at home and learnt Āyurveda from his father and, later, from Sant Īshar Siṅgh and Paṇḍit Jai Diāl. Early in his life he came under the influence of Siṅgh Sabhā enlightenment and founded in 1894 the Khālsā Vidyārthī Sabhā, lit. Sikh Students' Association. In April 1905, he established the Khālsā Bhujhaṅgī Sabhā, Sikh Youngmen's Association, which was affiliated to the Chief Khālsā Dīwān in 1908 and ultimately merged with the Siṅgh Sabhā, Tarn Tāran, in 1915. Bhāī Mohan Siṅgh was a member of the committee set up by Khālsā Dīwān Mājhā to open an institution for training workers to preach religious and social reform among the Sikhs, and when, as a result of the committee's recommendations, Khālsā Prachārak Vidyālā came into existence at Tarn Tāran in November 1906, he was appointed its secretary. In December 1907, the Chief Khālsā Dīwān set up the Sikh Handbill Committee to bring out leaflets to propagate Sikh principles. Bhāī Mohan Siṅgh Vaid, who had already floated a monthly magazine Dūkh Nivāran (January 1907) and had been a sub-editor of the Khālsā since February 1905, was entrusted with the writing of the handbills. He brought out 43 handbills during 1908-11 in hundreds of thousands copies in Punjabi, Hindi and Urdu on a variety of topics such as evils of drinking, gambling, ill-matched marriages, caste system and untouchability. He was also an active member of the Temperance Society, and became a municipal commissioner in his home town in 1910 which position he held throughout his life. A member of the Shiromaṇī Gurdwārā Parbandhak Committee since 1921, he was arrested on 7 January 1924 after the committee had been outlawed by government on 12 October 1923. He served a two-year term in Miāṅwālī jail from where he was released on 20 November 1925. He was again elected a member of the Shiromaṇī Gurdwārā Parbandhak Committee in 1930 as well as in 1933.

         Bhāī Mohan Siṅgh was one of the pioneers of modern Punjabi prose who rescued it from the conventional modes, introducing a simple, matter-of-fact style of writing. He wrote nearly 200 tracts and books on topics varying from religion, social reform, medicine and health care to politics, economics and psychology. Besides writing many novels, stories, essays and a couple of plays, mostly didactic in nature, he also published translations or adaptations of some western classics. Some of his more important works (other than those on medicine) are Dampatī Piār, Raṅg Baraṅge Phul and Hīre dīāṅ Kaṅīāṅ (fiction); Birdh Viāh Durdashā Nāṭak (play); Rabbī Joṛ Melā (mysticism); Karam Yog, Bacon Vichār Ratnāvalī and Ātmak Unnatī (ethics) ; ’Ilm Khyāl sub-titled Law of Mentalism (psychology); Kiṛe Makauṛe (zoology); and Grahi Parbandh Shāstar (household economics). One of his pioneering efforts to propagate gurbāṇī among the non-Punjabi readers was the publication in 1928 of the Gurū Granth Sāhib in the Devanāgarī script. He was a keen book lover, and a voracious reader. His biographer records that in 1931 at least 26 different papers and periodicals, mostly in Punjabi, were regularly received by him. His collection of books, magazines, pamphlets and newspapers has since been donated by his descendants to Punjabi University, Patiālā, and it constitutes a rare bibliographical resource in Northern India.

         Bhāī Mohan Siṅgh Vaid died at Tarn Tāran on 3 October 1936.