Question

How is this a synecdoche: "Take thy face hence."? What does this quote mean: "When to the sessions of sweet silent thought..."?

Answer 1

Hint: The synecdoche is the figure of speech in which the section of something is most commonly used to refer to its entirety. It often appears in everyday speech, often as part of idioms that have become so well known that few people ever stop worrying about the fact that what they actually say does not mean these phrases.

Complete answer:
A synecdoche is the part of speech in which one word or term is used in the place of the other to describe another word or term.
In the order, "Take thy face hence," the speaker does not tell the person to whom it is ordered to take their face to another place; they claim that they want someone else to go somewhere altogether.
The word "face" is used to refer to the whole body of the recipient. Instead, the sentence could read "Take thyself hence," ordering someone to move not only their face but their entire body.
In the usage of the term "face," the synecdoche occurs to refer to the entire body of someone.
The line you quoted is from the Sonnet of Shakespeare. Within meaning, the line makes more sense, so here are the sonnet's first three lines (Sonnet 30):
"When to the sessions of the sweet silent thought
I summon up remembrance of the things past,
I sigh at the lack of many things I sought..."
A "session" is just a time period. The speaker remarks that in "sweet silent thought," they always get lost spending time during which they recall things that have happened to them ("remembrance of things past") and become depressed thinking about things they expected, but never got ("I sigh the lack of many things I sought").
Therefore, the line "When to the sessions of sweet silent thought" is just the speaker's introduction to their argument about the personal time they spend thinking and reflecting on their history.

Note:When a part stands in for a whole, or a whole stands in for a part, a synecdoche happens. It is helpful to realize that there are various kinds of holes and parts to recognize synecdoche. In all kinds of literature, from fiction to poetry, Synecdoche often commonly appears.