 One of his brothers became an architect in Hamburg, whilst another (Hendrik Johan Kessels) became a famous clock maker in nearby Altona.Mathieu was first apprenticed to a goldsmith in Venlo but soon gave up his apprenticeship to attend the École des Beaux-Arts in Paris.In 1806 he made his way, via Hamburg, to Saint Petersburg where he abode eight years, learning how to make wax models and sculptures of various kinds in the workshop of Joseph Camberlain.