Read the excerpt from act 5, scene 1, of Julius Caesar . CASSIUS: Messala. MESSALA, standing forth. What says my general? CASSIUS: Messala, This is my birthday; as this very day Was Cassius born. Give me thy hand, Messala. Be thou my witness that, against my will, As Pompey was, am I compelled to set Upon one battle all our liberties. You know that I held Epicurus strong And his opinion. Now I change my mind, And partly credit things that do presage. Coming from Sardis, on our former ensign Two mighty eagles fell, and there they perched, Gorging and feeding from our soldiers’ hands; Who to Philippi here consorted us. This morning are they fled away and gone, And in their steads do ravens, crows, and kites Fly o’er our heads and downward look on us, As we were sickly prey. Their shadows seem A canopy most fatal, under which Our army lies ready to give up the ghost. MESSALA: Believe not so. CASSIUS: I but believe it partly; For I am fresh of spirit, and resolved To meet all perils very constantly. Which central idea does this speech about omens best support?