The main idea of the poem is "painful old age". The poem explores the physical and emotional toll that old age takes on an individual, highlighting the pain, decay, and loss of strength that often accompany the later stages of life. The poet presents a bleak and somber depiction of old age, emphasizing the hardships and challenges faced by the elderly.

1. Introduction:
The poem focuses on the theme of old age and its associated difficulties. It delves into the various aspects of the aging process and the impact it has on the individual.

2. Description of physical pain:
The poet describes the physical pain experienced by the elderly. Lines such as "wrinkled deep with pain" and "shrunk shank" depict the physical toll that old age takes on the body. The use of imagery and vivid language helps to convey the intensity of the pain felt by the elderly.

3. Loss of strength:
The poem emphasizes the loss of strength that accompanies old age. The poet describes the "thighs, shanks, knees" as weak and feeble, highlighting the diminished physical capabilities of the elderly. This loss of strength further contributes to the overall theme of painful old age.

4. Emotional suffering:
In addition to the physical pain, the poem also addresses the emotional suffering experienced by the elderly. Lines such as "Is its agony or the sorrow," suggest a sense of despair and sadness that accompanies old age. The poem explores the emotional toll that aging takes on an individual, adding depth to the theme of painful old age.

5. Reflection on the inevitability of old age:
The poem serves as a reflection on the inevitability of old age and the universal experiences of aging. It presents a realistic and raw portrayal of the challenges faced by the elderly, reminding readers of the fragility and transience of life.

Overall, the main idea of the poem is the painful nature of old age. Through vivid descriptions, the poet portrays the physical and emotional suffering experienced by the elderly, highlighting the difficulties and hardships that come with the later stages of life.