When you are at sea, or on the waterways of the kind of flat countryside that we see in these two paintings, the horizon always seems low. The sky dominates; there are no hills or buildings around you to distract the eye or give the scenery a sense of distance and depth. If you stop and contemplate the view, it is the clouds that become the most dramatic feature, and the drama they create is emphasised by the way the light changes as they build, disperse and scud across the sun, and by how it reflects back from the surface of the water.

Jan van Goyen, whose customers lived and worked in an environment of huge skies and constantly changing weather, mirrored this experience in many of his landscapes and seascapes. In both of these paintings – and as was typical in his work – he has set the horizon so low that the vast majority of the picture is taken up by sky. Apart from a few glimpses of bright blue, he has used shades of grey to evoke the billowing clouds and the passing curtains of mist or rain. The church and the windmill in the distance and the dark reflections on the water in the foreground are also depicted in greyish – yet luminous – tones of green, yellow and brown.

Both of these pictures are of identical size and seem to have been made to hang side by side. With a pair of paintings, Jan van Goyen could engage viewers in a more complex way than he could with a single picture. There are some striking similarities between the two: the low horizons, the islands or mudflats in the middle ground, the outlines of distant buildings, the angle of the navigation marker on the left, the three boats in similar positions in the foreground of each picture. But there are also many subtle differences. The two distant churches may be at a similar point on the horizon, but one has a tower and the other a spire. One navigation marker has two balls at the top, the other only one. In one painting, the clouds are slightly darker, but the distant light is clear; in the other, there seems to be a veil of mist or drizzle across the scene. And while in one the boats are stationary, in the other they are under way.

The two scenes also seem to be set at different stages of the tide. In A River Scene, with a Hut on an Island, it appears to be high water. The muddy shores are covered and we see only greenery on the island. Indeed, it must be near the top of the tide because if the water was much higher, it would inundate the hut. In the other painting, Fishermen hauling a Net, the tide has clearly ebbed and the mud flats are exposed.

By making these comparisons and contrasts, van Goyen is encouraging us to look more closely at each painting. Only by careful attention can we decide whether he has painted two different scenes, or the same view at a different state of the tide. Perhaps he was suggesting that, in both landscapes and paintings, the more we look, the more we see.