Answer: This passage describes the external conflict with cassius, because Brutus refers Cassius as a 'hot' friend, which means the he is angry.
Explanation: According to Lucillius, Brutus describes that the friend is angry and yet calm and according to him this happens when love starts to dissolve between two friends,
According to Brutus, Cassius is trying to be polite instead of the warm greetings that is exchanged between close friends. Brutus compares Cassius with horses, as when they are angry they show off their courtesy but when the time comes to take actions they sink into the war and justifies the conflict.