“Ninetieth Birthday” is not a particularly complex poem thematically; it reveals the cultural difference between people of earlier and later generations. Such a difference is not stated; rather, it is implied by the phrases such as “lost village,” “a place that exists/ In her memory only,” and “words that were once wise.” When one steps outside the poem to look at its author and the time of its writing, however, other related meanings emerge. Thomas is Welsh, and many of his poems are about the changes in Welsh culture, language, and history. Thomas’s poem “Welsh History” presents an image of Wales trapped in the past, the people, having lost their language, confined by their own history of poverty and violence. In the poem “Expatriates,” Thomas describes Welsh people leaving the mountains for the city and leaving their language behind. When one reads “Ninetieth Birthday” with an awareness of the changes in Welsh culture, the old woman’s separation from the visitor is even stronger.
“Ninetieth Birthday” was published in the volume Tares in 1961. If the poem is supposed to be taking place at the time of publication, the old woman would have been born in 1871. In 1871, many Welsh people did not speak English, a condition that had changed by 1961; furthermore, the number of people who spoke Welsh decreased substantially over the same period. With increases in technology, cars replaced horses, and tractors replaced the old horse-drawn ploughs. The old woman’s farm seems to be a farm caught in the nineteenth century, her words of wisdom applying to a time that is long gone. The second line of the poem describes the track as one “That will take a car, but is best walked”; the modern world and the old woman’s farm do not connect. The visitor’s sadness is not only about the old woman’s aging but also about how the world has changed so that the old woman no longer fits in with it. What has been lost is a culture, a way of living, perhaps even a language. The “history” in the first stanza becomes, in the second, a history that encompasses loss and alienation: Time cannot be reversed to counter aging, and it cannot be reversed to alter changes in a culture.