Read the excerpt below and answer the question. Every change of season, every change of weather, indeed, every hour of the day, produces some change in the magical hues and shapes of these mountains. When the weather is fair and settled, they are clothed in blue and purple, and print their bold outlines on the clear evening sky but, sometimes, when the rest of the landscape is cloudless, they will gather a hood of gray vapors about their summits, which, in the last rays of the setting sun, will glow and light up like a crown of glory. What theme is highlighted in this excerpt?