Observe how this works. Since the modern artist sees light in shadows, he also sees color in them. And their color varies according to the quality of the light and according to the local color of the spot affected. The local color of your lawn is green; therefore, even under the trees, where little light reaches the grass, the latter will still contain a greenish hue, though the value of it will be much lower than that of the sunlit lawn. On the other hand, the hue of the shadow will also be affected by the quality of the light, differing according as the light is dull or brilliant, and as it inclines to white or yellow. This is too intricate a subject to attempt to discuss here, but I mention it in order that, if you are wide awake and interested, you may amuse yourself by studying these effects in your walks abroad.