His earliest known painting is the "Vanitas still life with a young Moor presenting a pocket watch" (at Ader (Paris) 9 April 1990, lot 61) which is dated 1657. This painting falls within the genre of the vanitas still life, which Gijsbrechts practised principally until the later 1660s. This genre of still life offers a reflection on the meaninglessness of earthly life and the transience of all earthly goods and pursuits. The term "vanitas" is derived from the famous line 'Vanitas, Vanitas. Et omnia Vanitas', in the book of the Ecclesiastes in the bible, which in the King James Version is translated as . The worldview behind the vanitas paintings was a Christian understanding of the world as a temporary place of fleeting joys and sorrows from which humanity could only escape through the sacrifice and resurrection of Christ.