Failure of the plot

In this passage, Cicero goes in depth into Catiline's conspiracy and why it failed.

M. Porcius Laeca was a man that went along with Catiline's conspiracy. Meetings with the other conspirators were held in his house. There was a plan where Catiline would prepare his army against Rome in Etruria. In addition to Catiline's delay in his plot against Rome, Laecus's girlfriend overhead the conspirator's conversation and told the Senate of Rome about his plot.

Cicero uses more rhetorical figures in this speech. Along with rhetorical questions, Cicero repeats himself in different ways to amplify what he was trying to say.
"Hic, hic sunt in nostro numero... In hoc orbis terrae sanctissimo gravissimoque consilio..." Here, here they are in our numbers... with the most sacred and most serious consul in the world...
"Ubinam gentium sumus? Quem rem publicam havemus? In que urbe vivimus?"
Where in the world are we? What kind of republic do we have? What city do we live in?

During Cicero's speech, he talks about
He talks about very detailed steps in Catiline's plot. He talks about where he was, where he wanted his army to go, and how he had a delay in his plan. Cicero includes that Catiline had planned to have Cicero killed in his sleep, but that was a failure, too.

Why Not Put Catiline to Death

This is the second part of Cicero's speech to the senators about Catiline's conspiracy. Here, he speaks to question the existence of Catiline.

"Habemus enim eius modi senatus consultum, verum inclusum in tabulis, tamquam in a vagina reconditum, quo ex senatus consulto confestim te interfecum esse, Catilina, convenit."
Yes, it is true, we have a senatorial decree of that kind, but having been put away in official records, just like having been put away in a sheath, and on the basis of that senatorial decree, immediately, Catiline, yit is now right for you to have been already killed.
In this line, Cicero talks about how Catiline is still alive because the senators have not taken action about his conspiracy, but since they have the right to do something about it, he should already be dead by that moment.

"Si te iam Catilina, comprehendi, si te interfici iussero, credo, erit verendum mihi ne non potius omnes boni serius a me quam quisquam crudelius factum esse dicat. Tem denique interfeciere cum iam nemo tam improbus, tam perditus, tam tui similis inveniri poterit qui id non iure factum esse fateatur."
I understand if you, Catiline, were ordered by me to be killed, I believe, I will have to fear not that all the good men may say that this was done too late by me, but that someone may say that this was done too cruelly. You will finally be killed at the time when no one any longer so wicked, so socially ruined, like yourself, is able to be discovered which I must admit that this is not done justly.
Cicero is saying that if someone, anyone, were to say that Catiline's death was done too brutally, it would look bad on Cicero, and he does not want that. He believes that Catiline should be put to death because of his actions but Cicero does not want to look like the bad person.

"Quam diu quisquam erit qui te defendere audeat, vivis, et vives ita ut nunc vivit, multis meis et firmis praesidiis obsessus ne commovere te contra rem publicam possis. Multorum te etiam oculi et aures non sentientem, sicut adhuic fecerunt, speculabantur atque custodient."
As long as there will be someone who might dare to protect you, you will live, and indeed you will live just as you live now, many of mine have been blocked by strong bodyguards for the putpose of you to be not able to stir up against the Republic. Though you are not aware of them, the eyes and ears of many people will watch and also keep guard over you, who is not feeling this, just as they have done up to now.
In this line, Cicero talks about the reason why Catiline would be alive if he continues to be. However, even though Catiline would still be alive, his life will continue on as it did at the moment. People will watch and be cautious about Catiline's actions so he does not cause destruction to the Republic until it is time for him to be put to death.