Why Plutarch reads him
Plutarch reads Crassus as the study of avarice in a man of real ability — the richest man in Rome, the third member of the First Triumvirate with Pompey and Caesar, whose immense wealth bought him a place at the summit of the Republic but never the military glory he could not stop craving. The platform reads him, with Plutarch, as the case of a man whose governing passion — the accumulation of money — both made him and finally destroyed him.
Character: the appetite for more
Plutarch's portrait centres on Crassus' acquisitiveness, which he treats as the master-passion that organised the man. Crassus made his fortune in the proscriptions and in Rome's fires (buying burning buildings cheap), and his wealth was the instrument of a political power exercised through patronage, loans and obligation rather than through arms or eloquence. The platform reads Plutarch's interest as moral and diagnostic: the same appetite that built the fortune could never be satisfied by it, and it drove Crassus, late in life and against all prudence, to seek the one thing money could not buy — the glory of a great conquest.
The political significance
Crassus' significance is as one of the three men whose rivalry and alliance broke the Republic. The platform reads the Triumvirate as the moment private wealth, private armies and private ambition openly displaced the constitution; Crassus supplied the wealth. His end is one of Plutarch's great cautionary scenes: hungry for the military reputation that Pompey and Caesar had and he lacked, he led an army into Parthia and was annihilated at Carrhae in 53 BCE, his death removing the balance between Pompey and Caesar and clearing the road to civil war. The platform reads the Parthian disaster as the point where Crassus' ambition reached beyond his competence and destroyed him and his legions together.
The lesson Plutarch draws
Plutarch pairs Crassus with the cautious Athenian Nicias — two wealthy men drawn to disastrous foreign expeditions beyond their power to manage. The platform reads the lesson under ambition and downfall: that a ruling appetite, even for something as apparently safe as wealth, distorts judgement, and that the craving to be what one is not — Crassus reaching for the soldier's glory — is among the surest roads to ruin. His death is also part of the platform's reading of how the Republic fell.