The speaker refers to October as the "season of mists and mellow fruitfulness" in order to praise and appreciate a season whose characteristics some may regard as less lovely than "the melodies of spring." On the contrary, one speaker believes that fall has its own "song" that is just as beautiful as spring. The word "mellow" here means "full of life or spirit; vigorous." Thus, the phrase "mellow fruitfulness" can be understood as an expression of optimism about the coming harvest. Autumn is known by many names, but "mists" and "fruity" are among them. Mists are visible clouds composed of liquid particles (i.e., droplets) that reflect light from the sun. They often appear near water surfaces during late summer and early winter. Autumn leaves become yellow, red, and brown after they drop off the trees in large quantities following hot summers. The color change is due to the fact that chlorophyll produces green colors in plants during this time of year. Once the leaves decay, other materials such as wood and dirt begin to show up, giving rise to the name "fall colors". Fruitfulness is another name for autumn because it is the time when fruits grow on trees. Therefore, autumn is referred to as the "season of mists and mellow fruitfulness."