Mirza Tahir Ahmad was a world-renowned homeopath. He took interest in the books collected by his father Mirza Basheeruddin Mahmood Ahmad. After trying a couple of remedies for his own migraine and his wife's long-standing ailment, he was fascinated by the efficacy of homeopathic remedies. Before his Caliphate, he was already treating thousands of visitors at the annual conventions. After his election, his expertise was called upon by Ahmadis all over the globe through letters, as well as by leading doctors in London. He had successes treating patients with cancer[citation needed] and AIDS. He embarked upon a program of training others through classes televised on MTA International. These lectures were later compiled in a book (below).