Izaac de Vries was the youngest son of Jacob de Vries and Sophie van der Klei. He got married in 1931 to Elsina Oudgenoeg from Leek. Her nickname was Ellie. They had a daughter called Sophie, and a son called Jacob Comprecht. The family lived in the Schoolstraat, later in the house of Jacob de Vries and Sophia van der Klei in the Tuinbouwstraat 15 in Winsum. They belonged to the few people in Winsum who owned a car.
The father of Izaac de Vries, Jacob de Vries, was the inventor of the 'Genuine Winsumer Ointment' which he officially patented under the trade name 'Opwinza'. Izaac de Vries took over the production and the sale of the ointment from his father. He furthermore also specialised as a butcher in smoking horse meat.
On 10 July 1940, the synagogue of Winsum was sold by the church council to the Moderne Winsumer Bestuurdersbond (a trade union organisation). The chuch council at that time consisted of Simon Benninga and Izaac de Vries.
Elsina was said to want to go to Palestine, but her husband did not believe that the Jews in the Netherlands would be prosecuted.
H. Hamburger and J.C. Regtien, Een joodse erfenis van Winsum (Bedum 1993) 9, 13, 23-24, 29; H. Hamburger and J.C. Regtien, Sporen van een joods verleden in Noordwest Groningen (Bedum 1995) 32, 35
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