Est mihi tanti, 'I think it worth while.'
falsae, 'misdirected.'
sane, 'by all means.'
non est iturus, stronger than 'ibit,' 'he has no intention of going.'
illud refers to what follows ('ne sit,' etc.). Cf. the use of ἐκεῖνο in Greek.
Quamquam, etc. 'And yet those, who keep saying that Catilina is going to Massilia, do not really regret, so much as fear it. No one of them is tender hearted enough to wish him to go thither rather than to Manlius.' If their motive were really (as they pretend) disinterested pity for Catilina, they would be glad to hear he had gone to Massilia, because that is his only chance of escaping destruction. The truth is that they are secret partisans of his schemes, and are afraid he may be going to abandon them by voluntary exile.
sanare sibi ipsos, 'to restore them to themselves,' i.e. to their right minds.