Asinius Pollio, a general who fought on Caesar's side throughout the civil war and who was present at the critical battle of Pharsalus, gives us Caesar's words when he saw his enemies--many of them his fellow citizens--dead or in flight after that battle (Suetonius preserves them, Caesar 30):

Hoc voluerunt. Tantis rebus gestis Gaius Caesar condemnatus essem, nisi ab exercitu auxilium petissem.

They wanted this. Despite my many achievements, I, Gaius Caesar, would have been condemned had I not sought the aid of my army.

The contempt and outrage in this statement could not more clearly express Caesar's famous inability to distinguish his political life from his life as a human being. The roots of Pharsalus lay in Caesar's desire to preserve his political existence, and the struggle was largely personal (though carried out with constitutional weapons until the civil war broke out). His personal/political enemies sought to prosecute him for illegalities while acting as the head of state, threatening to indict him should he ever lose the protections of his army and his immunity to prosecution as an official away (in Gaul) on state business. When his critical protections looked like they were about to evaporate, he marched south on Rome.

At the beginning of the civil war of 49, Pompey the Great wrote to Caesar, his erstwhile "friend" and political ally, to excuse his actions, pretending somewhat obtusely to see only the interests of the state as against all other claims:

velle Pompeium se Caesari purgatum, ne ea quae rei publicae causa egerit in suam contumeliam vertat. semper se rei publicae commoda privatis necessitudinibus habuisse potiora. Caesarem quoque pro sua dignitate debere et studium et iracundiam suam rei publicae dimittere neque adeo graviter irasci inimicis ut, cum illis nocere se speret, rei publicae noceat. (BC 1.8.3)

Pompey wanted to clear the record: Caesar shouldn't take it personally that Pompey was acting on behalf of the state. He had always considered the advantage of the Republic more important than his personal obligations. For the sake of his political standing, Caesar, too, ought to help the Republic by letting go his partisan hatred and resentment. He ought not be so angry with his personal enemies that in trying to get at them he might harm the state.

Caesar, who was not above using clever language to advance his cause, gave a terse reply on this occasion--he has no sense that he is in the wrong at all, and willingly reveals his "honest" self interest in order to contrast it with Pompey's swinish tergiversation (before going on to expound a catalogue of complaints, to be sure):

sibi semper primam fuisse dignitatem vitaque potiorem. (BC 1.9.2)

This brief indirect sentence: "his political standing had always come first for him, even before his life," throws Pompey's pious cant about fighting for the state back in his face: though motives are rarely simple, most people could see that Pompey was following his own interests in making common cause with the fanatical oligarchic faction which hated Caesar. Caesar even appropriates Pompey's syntax and throws it right back at him (semper se . . . potiora -- sibi semper . . . potiorem).

There is always danger of writing a defense of Caesar while attempting to look at him closely. His bravery and intelligence compel admiration, and in many important respects he shines out against the dull background of his contemporaries. But he acted consistently as though the rules did not apply to him, and ended up killing perhaps a million people in his career, often in circumstances meant to advance or preserve that career.

Caesar's overriding interest in his political standing and the struggle with Pompey and the other "optimates" are well known and have been studied by many people. Perhaps the best study is
Raaflaub, Kurt A. 1974. Dignitatis contentio.

The translations are mine, and I have deliberately strayed from literality here and there to preserve the "feel" (or highlight the subtext) more accurately.