Which of the following literary devices is used in these poetic lines by John Milton?

How soon hath Time, the subtle thief of youth,
Stolen on his wing my three and twentieth year!
  1. Metonymy
  2. Personification
  3. Simile
  4. Paradox

Before we can decide which of the above literary devices Milton used in his poem, On His Being Arrived to the Age of Twenty-Three (1631), we must first understand all of our options.

First, let's consider metonymy. Metonymy means to substitute one word for another which has attributes associated with the overall idea being conveyed. For example, when we say, "He was fishing for information," the word "fishing" represents stealth and the idea of someone slyly collecting information by luring out what they want to know.  Other examples of metonymy are, "She really hogged the microphone!" and, "The pen is mightier than the sword."

The second option, personification, is a technique whereby an author turns a thing or an idea into a person by giving it human qualities or personality traits. Things in nature are oftentimes personified in poetry and prose. Some good examples of personification are, "The sun smiled upon the fields," and "The angry ocean swallowed the ship whole."

The third technique, simile, is used when comparing things that seemingly have like qualities. Generally speaking, whenever things are compared using the word "like," you're using simile. For example, the phrase, "My love is like a red red rose," is a simile. Another example is: "The road stretches before me like a ribbon."

A paradox is a puzzling or seemingly contradictory idea, which is possibly true nonetheless.  The writer Oscar Wilde (1854–1900) was a master of the use of literary paradox. Here are some good examples from Wilde's writings: "I can resist anything except temptation," and "Everything popular is wrong."

Now, considering the definitions and examples presented above, can you determine which literary technique applies best to Milton's lines? Of course, the correct answer is personification, since the poem speaks of Time as a winged thief, who is stealing away the author's youth. Here's the full text of Milton's poem. Can you find more examples of personification or other literary techniques here?

On His Being Arrived to the Age of Twenty-Three

HOW soon hath Time, the subtle thief of youth,
  Stolen on his wing my three and twentieth year!
  My hasting days fly on with full career,
  But my late spring no bud or blossom shew'th.
Perhaps my semblance might deceive the truth,
  That I to manhood am arrived so near,
  And inward ripeness doth much less appear,
  That some more timely-happy spirits indu'th.
Yet be it less or more, or soon or slow,
  It shall be still in strictest measure even
  To that same lot, however mean or high,
Toward which Time leads me, and the will of Heaven,
  All is, if I have grace to use it so,
  As ever in my great Task-master's eye.

—John Milton, (1608–1674)