Try chasing your own shadow across a sunny playground and you learn Jonson's lesson quickly: the harder you run at it, the faster it slips away. Walk off with your back turned and there it is again, stuck to your heels. Jonson takes this everyday trick of light and turns it into a joke about courtship. Then, more slyly, he turns it into an argument about who really holds the power between men and women.
The first stanza works like a seesaw. "Follow a shadow, it still flies you; / Seem to fly it, it will pursue." The verbs swap places, and the same pattern is applied to love: "court a mistress, she denies you; / Let her alone, she will court you." The word "court" changes hands within a single line. At first it is the man's action, and by the end it is hers, so the sentence performs the reversal it describes. "Mistress" is worth a second look too. In love poetry it means the beloved, but it also means a woman in charge. The speaker thinks he is describing a shadow and keeps accidentally describing a ruler.
Then comes the refrain, a question that fishes for a nod: "Say, are not women truly then / Styled but the shadows of us men?" "Truly" and "but" pile on the pressure, yet "styled" quietly undermines it. To be styled something is to be called it, so all the speaker has proved is that women are labelled shadows, not that they are. Whether Jonson meant that hedge or not, it is there to be noticed.
The second stanza swaps the chase for the sun. Shadows are longest at morning and evening and "short or none" at noon. The application follows: "So men at weakest, they are strongest, / But grant us perfect, they're not known." Here "they" are the women. When the sun is low and men are at their weakest, the shadow stretches far. When a man stands at his height, directly under the sun, it vanishes. "Grant us perfect" has the smugness of a debater making a concession he expects to win anyway.
The comparison, though, cuts both ways. A being that is strongest exactly when the man is weakest is hardly a faithful copy. In the first stanza the shadow also does the opposite of whatever he wants. A copy that always does the opposite is not much of a copy, and the poem's own logic hands the shadow a power the speaker does not seem to notice.
The form helps the trick along. Each stanza has six lines rhymed *ababcc*, and the closing couplet is repeated word for word. Repeating it makes it sound like a settled conclusion, even though the evidence in each stanza is different. The lines are mostly brisk four-beat iambics of about eight syllables, but they alternate with nine-syllable lines that end on a soft extra beat: "flies you," "denies you," "longest," "strongest." These double rhymes give the verse a light, skipping lilt that reads almost like a song. That charm makes the argument feel easy and friendly, which is when an argument is most worth checking. The "none" and "known" pair is only a near-rhyme to a modern ear.
The pronouns shift too. In the first stanza four lines end on "you," pinning the reader as the man being teased and fooled. In the second, the poem moves to "us" and "they." The anecdote becomes a general rule, and the speaker gathers his male listeners into a club. Judging by this poem, Jonson, the English poet and dramatist of the late sixteenth and early seventeenth centuries, valued economy: twelve short lines, one image, and little wasted.
The poem is significant as a neat example of the witty argument-by-comparison, where a single image is pushed until it seems to prove something. It also teaches suspicion of such images. A metaphor can feel like evidence while really being a trap, and this one half-springs on its own speaker. Modern readers will likely resist the old stereotype that women are contrary and fickle, but the poem's real pleasure lies in watching its logic wobble. Is Jonson sincerely complaining, or teasing the complainers? The poem never says, and that ambiguity keeps it lively.