On the death of these great men [Rembrandt, Ruysdael and Cuyp] Landscape rapidly declined; and during almost the whole of the succeeding century, little was produced.. .From this degraded and fallen state it is delightful to say that landscape painting revived in our own country [England], in all its purity, simplicity, and grandeur, in the works of Wilson, Gainsborough, Cozens, and Girtin.
Notes from Wikiquote
having discussed the important role of Rembrandt in landscape painting and mentioned the significance of Ruysdael and Cuyp, Constable identifies a decline in landscape painting in Europe