Ninetieth sonnet of William Shakespeare refers to the thematic group of sonnets addressed to the friend, to the sub-group of poems, telling of the rivalry and jealousy of other poets.
The main idea of the piece the deadly impossibility of losing a loved one in the background up in arms against the poets of the world. It should be noted that "loss" can be understood not only a friend but a lover and because the adjective "last" has no explicit sexual designation. The last interpretation was frequently used by Russian translators of Shakespeare, giving the ninetieth sonnet romantic overtones. Original context operates military metaphor (the world as the battlefield, you, the onslaught of attack) and more characteristic of friendship than love between a man and a woman.
The first quatrain paints a mental state of the lyrical hero and shows external circumstances used as a basis for poetic treatment. Got in disgrace of the whole world, appealed against his works, the Poet tries to ease their plight, offering a friend to join the fate of the evil right now. Why? The explanation is given in the second quatrain.
Here the lyrical hero says, that it can resist befell his sorrow, but if a friend comes in the rear defeated grief, he will prolong the pain that would end final defeat. Offer other to hate him "now" the Poet is trying to protect itself: to be closed from the only real attack that can destroy his heart. All the troubles of the world for the lyrical character a windy night, but the loss of a beloved friend a rainy morning is a continuation of grueling misery.
In the third quatrain, the Poet again turns to the other, not wanting to, but avoiding the idea that will be left. If that happens, he wants the other "the last of the outgoing", after appearing in "the total onslaught of attacks" he will be able to subject him to the worst stroke of fate.
"Sonata castle" is such a strange desire lyrical, loving friend, but the fact of the matter asking him about hate: the terrible grief can turn the current problems into small, invalidate them, and thus give a good chance to win. The poet would have coped with the world without such extravagant means, but he, like all lovers, too cherishes the fact that it is expensive, and clearly understands what the loss of a friend can finish. Wiser to play it safe, to predict in advance the possible scenario, and ask a friend for mercy: either to be with him until the end (and read between the lines), or you can leave right now.
Ninetieth sonnet is written in pentameter. In the first two quatrains feminine rhymes alternating with masculine. The third quatrain and "castle" are masculine rhymes.