Gebirgige Ideallandschaft mit ziehenden Hirten. 1661.
Oil on canvas.
Signed "G. M(?)aasius." and dated lower center. 61,5 x 84,5 cm (24,2 x 33,2 in).
This painting is the artist's oldest dated work, whose creative period can now be said to have lasted from 1661 to after 1709. The Rijksbureau voor Kunsthistorische Documentatie knows of a similar painting from 1691.

With a writing (in copy) from Marijke C. de Kinkelder, Rijksbureau voor Kunsthistorische Documentatie, The Hague, from 31 December 2007. The painting is listed in the RKDimages under the no. 21277.