Born in Boitsfort, Belgium 1883, died 1969; born in a well-to-do Walloon Belgian family; in 1905 he became acquainted with the anarchist commune of Emile Chapelier, which was located in Stockel-Bois from 3 April of that same year and later transferred to Boitsfort, both near Brussels; the commune, named 'L'Expérience' (the Experiment) and with the parole 'Nous n'avons ni dieu ni maître' (We have neither God nor master), was dedicated to the principles of common property, free love, vegetarianism, anti-militarism and anti-colonialism; those who joined later included Dutch deserters; in February 1908 the colony fell apart as a result of internal tensions and external opposition; Marin fled to England and joined the anarchist-Tolstoyan Whiteway Colony near Gloucestershire; he lived there until his death.

The papers were donated to the IISH by Michael Grendon in 2006.

Photocopies of a handwritten diary including a report by Emile Chapelier and Gassy Marin on the communist-libertarian colony near Brussels 1905-1908; proposal for experimental cooperative communities in Mexico 1923; food distribution ration books 1939-1954; some documentation 1911-1964.