Fosie was a wealthy man; he busied himself with mechanics and linguistics, and was for several years organist at the Church of Holmen and as such undoubtedly an accomplished musician, although he once admitted that he was not practicing music outside of Sundays.
Fosie var en velhavende mand; han syslede flittig med mekanik og sprogvidenskab, var i en række år organist ved Holmens Kirke og som sådan uden tvivl en habil musiker, skønt der ganske vist meldes, at han ikke øvede musikken uden om søndagen, og at der i hans eget hus aldrig rørtes noget instrument.