What is the purpose of the separation of powers in a presidential form of government?

Read the excerpt below and answer the question. and i live on, but in grief and self-contempt, left here without the light i loved so much, in a great tempest and with shrouds unkempt. no more love songs, then, i have done with such; my old skill now runs thin at each attempt, and tears are heard within the harp i touch. (lines 9-14) which of the lines, taken from the sestet shown above, is the volta?

Me asap i will mark you as brilliant

Explain what the following quote means: “if men are naturally in a state of war, why do they always carry arms and why do they have keys to lock their doors? ”