In Act 4, Scene 3, after the heated argument between Brutus and Cassius in Brutus's tent, a Poet intrudes on them, and the following exchange occurs:
LUCILIUS[Within] You shall not come to them.
Poet[Within] Nothing but death shall stay me.
Enter Poet, followed by LUCILIUS, TITINIUS, and LUCIUS
CASSIUSHow now! what's the matter?
PoetFor shame, you generals! what do you mean?
Love, and be friends, as two such men should be;
For I have seen more years, I'm sure, than ye.
CASSIUSHa, ha! how vilely doth this cynic rhyme!
BRUTUSGet you hence, sirrah; saucy fellow, hence!
CASSIUSBear with him, Brutus; 'tis his fashion.
BRUTUSI'll know his humour, when he knows his time:
What should the wars do with these jigging fools?
CASSIUSAway, away, be gone.
It is hard to understand why Shakespeare included this episode in a scene which is already quite long and will get much longer. The best explanation is that he felt the need for a bit of comic relief after the argument so full of threats, recriminations, insults and invective between the two generals. Brutus is usually so considerate and courteous that he may feel guilty for having treated Cassius in such an harsh and disrespectful manner. The intrusion of this silly poet may have given Brutus an excuse to turn his wrath against someone other than his friend and partner.
The Poet's intrusion also provides a plausible reason for the entrance of Lucillius, Titinius, and Lucius, all of whom are trying to prevent the crazy Poet from imposing his unwelcome advice and his stupid poetry on two great men who are having a meeting of historic importance. The arrival of the three subordinates gives Brutus occasion to issue some military orders to Lucillius and Titinius and to ask Lucius to bring a bowl of wine.
Both Brutus and Cassius need a good drink after the violent emotions they have experienced in an argument which threatened to end in bloodshed. It is interesting to see how Cassius reveals his character in nearly everything he says. For example:
BRUTUSGive me a bowl of wine.
In this I bury all unkindness, Cassius.
My heart is thirsty for that noble pledge.
Fill, Lucius, till the wine o'erswell the cup;
I cannot drink too much of Brutus' love.
Cassius cannot drink too much of Brutus's wine, either. Cassius is a selfish, greedy miser. A miser will betray his character even in little things. Misers are typically freeloaders. They always get more than they give. Brutus will probably take one sip of wine and Cassius will finish off the entire bowl and possibly ask for a refill. He knows Brutus will have good wine, whereas Cassius probably never has such wine even at home for his exclusive consumption.
Casca has known Cassius all his life. In Act 1, Scene 2, when Cassius invites him to his home for dinner, Casca very rudely accepts:
Ay, if I be alive and your mind hold and your dinner
worth the eating.
Casca knows what kind of entertainment to expect at the home of Cassius, where the servants look browbeaten and half-starved, and where the wine will have the bitter aftertaste that betrays a cheap vintage reserved for visitors.
It is noteworthy that even after winning his argument with Cassius, Brutus still doesn't have the gold he needs to pay his troops. He may have forgotten about it temporarily, what with all the other matters requiring his attention; but not paying his troops on time might explain why they fight with less enthusiasm at the Battle of Philippi.