What should I do with an essay question that's just a quotation?

Let's begin with an example.

"What immortal hand or eye, / Could frame thy fearful symmetry?"

Hypothetically, this question would be from an A2 examination on William Blake. As is more common at higher level learning, this is a question without a question. 

First, it's important to really take a long, hard look at the question. The first thing that we notice is that there is no fixed framework, such as "How did William Blake view religion?". All we have is the quotation, so it's important to make good use of that. 

So, what is the quotation gesturing towards? The "immortal hand or eye" refers to a higher being, such as God. Knowing William Blake, however, we know that his relationship with God and the Church wasn't so simple.

Deconstruct what we are looking at further, examining the "hand or eye". What's the difference between the two in this instance? God's hand framing the tiger's symmetry shows us an active God, whereas God's eye being responsible for framing the tiger places emphasis on his vision. What the section is really asking here, then, is how close is God to business here on earth?

Now we have two key topics to work with, you can start arranging your ideas for the essay. The quotation is broadly concerned with God's involvement with relationship to nature, and by extension man. Within this, you could talk about the Church, moving onto Blake's many poems criticising them. What's critical, however, is setting yourself a task to complete, a problem to be solved, since the question does not do that for you.