Constant grew up in a Catholic environment and attended Saint Ignatius College, a Jesuit college in Amsterdam. In 1936 he painted his first oil painting and chose a religious subject: “The Emmaus Travellers”. Constant painted this work on an old burlap sack and used pigment from a house painter that he bought with his pocket money. Soon, other works of art with religious themes would follow. Not much later, however, he distances himself from the church and during WW II there is a definite break.