Dan Isaac Davies was a schoolmaster and patriot. He is best known for pioneering the teaching of Welsh in schools. Davies became master of Mill Street School in Aberdare in 1858 where he contravened some conventions that were imbedded into education in Wales at the time. By encouraging his assistant to use Welsh within the walls of the classroom, Davies broke new ground and began his quest to teach the language at schools in Wales. After being appointed a School Inspector in 1868 he intensified his campaign regarding Welsh education. A similar venture was initiated by the Cymmrodorion Society and in 1885 Davies read a paper on the subject before its members in London. In the very same year he contributed a series of articles, again on the subject of teaching Welsh in schools, to the ‘Baner’; these were reprinted in a volume under the title ‘Tair Miliwn o Gymry Dwy-ieithawg mewn Can Mlynedd’.