What is the purpose of citing textual evidence in a literary analysis essay?

At last it was settled by lot that zeus should reign supreme in heaven, whilst aides governed the lower world, and poseidon had full command over the sea, but the supremacy of zeus was recognized in all three kingdoms, in heaven, on earth (in which of course the sea was included), and under the earth. zeus held his court on the top of mount olympus, whose summit was beyond the clouds; the dominions of aides were the gloomy unknown regions below the earth; and poseidon reigned over the sea. what element of a myth does this excerpt contain? an example of an historical event a lesson about human behavior an explanation of an event in nature a story about gods or goddesses

How now how now chop logic what is this proud and i you and i you not and yet not proud mistress minion you me no nor proud me no proud

What do technical writers need to do when using an image?