Now I particularly wished you to notice that the head suggested to us that hardness of the skull and the varying firmness and tightness of the flesh. For it proves that the softening of the outline will not interfere with the feeling of hardness and strength, or firmness in the mass. The effect, indeed, is to increase it, since out attention is concentrated on the head and not distracted to the outline. On the other hand, do not suppose that the softening of outlines is always intended to increase the suggestion of solidity. It may be part of an entirely opposite intention; namely, to lose sight of the idea of solidity of mass. For example, the French landscape artist, Corot, often represented the masses of the trees as soft, dark blurs against the soft light of the sky. For he loved especially the early dawn and late evening, when the light is very faint and in the hush the trees loom up like quiet spirits. He wished you to feel their presence, but not to be conscious of their solidity and bulk. He, you see, used the softened outline for a different purpose; which shows that in art, as in other matters, a single principle may be applied variously in different cases.

These tree-presences of Corot are painted very flatly. The roundness of their bulk disappears into a flat mass. It was one of the ways in which he avoided the suggestion of solidity. But here again comes in the fact that a principle may have other applications; for flatness does not necessarily make the object appear unsubstantial. A house does not look so, yet its front may be flat. And Corot, as other artists, and as you may, if you use your eyes, had discovered that in the open air all objects appear flatter than they do indoors. The reason is that in the case of a room lighted by windows, the light is always stronger near the windows than it is in parts of the room further removed. The light is unequally distributed, so that there are more shadows to throw up the bulk of objects. But out of doors the light is more diffused; more equally distributed. Moreover, we view things from a greater distance, so that more atmosphere intervenes. The effect of both these facts is to make the masses of objects seem flatter. The lawn from a little distance may look very smooth; but, when you walk over it, you find the grass needs to be cut and the bumps to be rolled before you can play croquet. That maple, too, is a sturdy, solid fellow, but as you see its mass of pale green against the darker mass of hemlock, both seem flatter than they do when you are climbing among their branches.

In speaking of the softening of outline and flattening of bulk due to atmosphere we have frequently alluded to the effect of distance on the appearance of objects. The further off the latter are, the more atmosphere will intervene, the less distinct will they appear. In the case of distant hills, the ups and downs of the ground, the bulk of the trees, even the stability and massiveness of “the everlasting hills,” may be softened and flattened into what seems to be only a faint mass of color.

Perhaps we have walked over these hills and know them to be carpeted with grass; the greens also of the maples, oaks, cypress, each with its separate hue, attracted our attention. But to-day, from a distance, all these greens are lost in a vaporous hue of blue. It is this effect of atmosphere on color that we will now talk about. It is easy to notice in the case of the hills because of the great quantity of atmosphere that intervenes between us and them. But, if there were a row of maples extending from the hills to us, so placed that we could look along their entire length, we should find the appearance of their color gradually changing, as they recede from our eyes. In a word, to the sensitive eye of the artist the colors of even nearby objects are affected by atmosphere.

Now, those hills appear to be blue; another day, they will incline more to grey; yet another day to violet or purple, or pinkish. In winter time, around New York, they would very likely take on a dry, whitish color. In fact, the color will vary according to the condition of the atmosphere and the quality of the light; depending upon how moist or dry, how warm or chill, the atmosphere may be, and whether the light is yellow or golden, grey or white, full or feeble, and so on. It is these constant variations of lighted atmosphere that give continually fresh interest to the beauty of nature. Nature never wearies us by being always the same. It is like a human face, whose expression is continually changing.

Sometimes we see a beautiful human face, with almost perfect features. But behind that beautiful mask may be a very dull, uninteresting mind. If so, the expression of the face will be passive, the opposite, that is to say, to active. It will not leap from grave to gay; kindle, sparkle, grow tender, or angry and joyful by turns. It will be—“faultily faultless, icily regular, splendidly null”—no expression. And we may even tire of its beauty; while a face, less perfect in features, may win us more and more and hold our interest by the charm of its continually varying expression. The more we think of it, the more do we realise that beauty depends upon expression. It is the same with nature as with the human face. Its beauty is affected by expression and this is produced by the varieties in the lighted atmosphere.

A moment’s thought will satisfy you of this. Nature’s features vary with the seasons, but change little from day to day. Every morning, during the summer vacation, the same objects greet your eye, but how differently you feel towards them, according to what we call the weather, which after all is the condition of the atmosphere. One day the familiar features of the landscape will take on an expression of gladness, some other day of dullness; and the more we study the features, the more variable will their expression appear from hour to hour, day to day, and season to season.

I spoke just now of the movement of the atmosphere. It is a fluid, that one day may be as still as a forest pool, another day may be stirred like the