[3] He took on pupils Willem van Santvoort, Jacob Grimmer and Jan Keynooghe.

[4][1] A portrait of Cock was included in the 1572 collection of portraits of early Netherlandish painters entitled Pictorum aliquot celebrium Germaniae inferioris effigies, accompanied by a poem about his landscapes written by Dominicus Lampsonius.

[5][6] The early biographer Karel van Mander stated in the Schilder-boeck of 1604 that Cock was the first to bring the southern manner of landscape painting to the North.

[4] His landscapes show that he was aware of the work of Titian and the Venetian draughtsman Domenico Campagnola.

[7] Cock has been suggested as one of the possible draughtsmen of the Errara sketchbook in the collection of the Royal Museums of Fine Arts of Belgium, but this attribution is not generally accepted.