松 means 'pine tree'

These essays showcase four types of trees that afford great pleasure. The Japanese love seeing rows of them along rivers, the seashore, and avenues (especially on the world's longest tree-lined road), and people famously picnic under cherry blossoms. To the Japanese, the pine, cedar, willow, and cherry also symbolize key qualities: transience and mortality (the cherry); longevity, vitality, and sincerity (the cedar); emotional flexibility, weakness, sadness, and thinness (the willow); and superior rankings (the pine). Moreover, these trees play key roles in the arts, such as haiku, woodblock prints, ink paintings, lyrics, Noh theater, and ghost stories.

Though the Japanese live longer than anyone, they pray for even more longevity—for humans and deities alike. These four auspicious kanji are associated with longevity, which is a natural fit for 亀 and 鶴; as one proverb has it, turtles and cranes live thousands of years. Meanwhile, 寿 means "lifespan" and "longevity" in words for those concepts and appears in many terms for milestone birthdays. Finally, because the pine represents long life, thanks to its evergreen needles, images of that tree abound at weddings and on New Year's cards. Similarly, twin pines symbolize a long, happy marriage.