Sea views occupy a position by themselves inasmuch as there is a fixed horizontal distance for the artist. He cannot shorten this depth without making his work look abnormal, and an effort to increase it by presuming that the picture is painted from a considerable height above the sea level, is seldom successful because the observer of the work finds a difficulty in fitting in the novelty with his experience. Except when depicting stormy weather, or showing a thick atmosphere, the painter of a sea view has no trouble in obtaining absolute accuracy in his linear perspective, but this is not sufficient, for if a variety of trees, herbage, brooks, and so on, requires an illusion of movement, then certainly does a sea view which has monotony for its keynote. The motion of the waves in fine weather cannot be suggested on canvas because it is continuous and equal. One wave displaces another and so far as the eye can reach there is only a succession of similar waves. Thus the motion appears unbroken, and from the canvas point of view the waves must be motionless as the sand hillocks of a desert. Of course in the actual view, the expanse, the "immeasurable stretch of ocean," is impressive and to some extent weird, but nothing of this feeling is induced by a painted miniature. With a bright sky and clear atmosphere the painter of a sea view cannot well obtain an illusion of opening distance by means of a multiplication of signs as on land, for the introduction of many vessels would give the work a formal appearance, but the problem can be satisfactorily solved by putting the sun in the sky towards the setting, and using cloud shadows as signs. Aivasovsky, one of the greatest marine painters of modern times, was very successful with this class of work. His long shadows thrown at right angles to the line of sight, carry back the distance till the horizon seems to be further off than experience warrants, the illusion being perfect. An illusion of opening distance may, however, be easily obtained in a sea view when there is a haze covering, but not hiding, the horizon, by introducing as signs, two or three vessels, the first in the middle distance. Another method of giving a suggestion of motion, which may be used by the sea painter, is in truthfully representing the appearance of the water round a vessel passing through it. What is probably the finest example of this work in existence is Jacob Ruysdael's The Rising Storm.[a] The sea is shown close to a port, and half a dozen smacks and small boats are being tossed about by choppy, breaking waves. In the centre of the picture is a large smack over the weather bow of which a huge foaming wave has broken, and part is spending its force on the lee bow, from which the water gradually becomes quieter till at the stern of the boat little more than a black concavity is seen. The progression of wave movement is completely represented, and the effect is very impressive. [a] Berlin Gallery. See Plate 20.