It depends what you are talking about in your essay and what kind of essay. You need to give some background before you put in your quote. If you just drop it in that is what we call a "quote bomb". So whatever your point for your paragraph is should already be introduced and explained before your quote and then all you have to say is something like, this can be seen in such and such book when this character explains that,"Ten thousand saw I at a glance, Tossing their heads in sprightly dance.”[ William]
