I've been thinking about what I call the "Renga Scenes", or "Renga Landmarks"; those topics that have specific locations in a Renga. These include verses for the Moon, verses for Flowering Trees, and verses on Love. What I've been contemplating is how these three topics encompass the cosmos, and that the Renga Journey becomes a kind of cosmic journey through the use of these specific topics.
The Moon Verses refer to the Heavens. One could also call them "celestial." The Moon, and its constantly shifting phases, is the most prominent, and beautiful, feature of the heavens from our perspective on planet earth.
The Flower Tree verses refer to the Earth, they are Terrestrial verses. Trees emerge from the earth, they are an expression of Earth, and in their flowering form they express the beauty of the Earth.
The Love Verses are verses focused on Humanity. Renga chooses the topic of "Love", rather than other kinds of human activities, such as work, study, politics, science, etc. I think this is because Love is to Humanity, what a Flowering Tree is to the Earth, and what the Moon is to the Heavens. In all three realms Renga focuses on specific manifestations that are both beautiful, heartfelt, and transient, constantly changing.
These three pillars of Renga, the Moon, Flowering Trees, and Love verses, serve to make each Renga a kind of microcosmos that reflects and instantiates the cosmos in which we live out our lives.