The opening stanza introduces the first speaker in the poem's dialogue. A "young man" addresses a man named "Father William," bluntly informing him that he's grown "old" and that his hair has turned "very white." Yet, despite his advanced years, Father William "incessantly stand[s] on his head"! In confusion or distaste, the young man asks, "Do you think, at your age, it is right?" In other words, should you really be doing acrobatics all the time?

What's going on here? Although most modern audiences won't catch the reference without guidance, Lewis Carroll is parodying—that is, mimicking and poking fun at—a poem that would have been familiar to his original readers. That poem is "The Old Man's Comforts and How He Gained Them" (1799), by Robert Southey, the one-time Poet Laureate of the UK. Southey's poem is serious and moralistic, as this opening excerpt shows:

You are old, Father William, the young man cried,
⁠The few locks which are left you are grey;
You are hale, Father William, a hearty old man,
⁠Now tell me the reason I pray.

In the days of my youth, Father William replied,
⁠I remember'd that youth would fly fast,
And abused not my health and my vigour at first
⁠That I never might need them at last.

It's no fun at all, but it was assigned to many schoolchildren of the Victorian period as a lesson in healthy, prudent, pious living. Sometimes students were assigned to memorize and recite the poem. In Carroll's Alice's Adventures in Wonderland, Alice herself tries to recite it to the Caterpillar—but to her surprise, instead of Southey's original, she stammers out this parody instead.

Notice that Carroll preserves some elements of the original, making the parody easier to recognize. His poem, too, begins with "You are old, Father William," a reference to the father's gray/white hair, and an acknowledgment of the old man's vigor. It also borrows Southey's rhymed quatrains and anapestic (da-da-DUM, da-da-DUM) meter.

However, Carroll also makes some important changes. Not only does he turn Father William into a clowning acrobat—comically exaggerating his health and vigor by having him do headstands—he also changes the rhyme scheme from ABCB to ABAB. The second is a little harder to pull off, and also a little more musical, so it's a subtle way of making the poem wittier and more pleasing to the ear. Southey hoped to instruct his young readers; Carroll hoped to entertain them!