Dickens isn’t exactly placing this metaphor delicately into his readers’ hands. He’s shoving it down our throats. If you missed the part where he warns us that blood will soon spill in the streets like wine, check out most of Volume One again. We promise you, it’s easy to find.
Using the wine that spills into the streets early in the novel as a metaphor for the blood spilled in the revolution serves a practical purpose: the Defarges run a wine shop. The Defarges are the hub of revolutionary activity. It all fits together neatly.
More important, however, allowing wine to stand in for blood allows Dickens to hint at the fatal flaws in the revolutionaries’ plans: too much wine makes people drunk and often more than a little crazy. A few glasses too many, and suddenly you’re not thinking nearly as well as you probably should be.
Similarly, spilling a little blood makes people hunger for more. Suddenly, it’s not enough to kill the people who’ve wronged the poor. It’s also pretty fun to kill their wives, their sons, their daughters, and that guy that people once saw standing next to them. See how things can get out of control? La Guillotine becomes a glutton, demanding more and more wine to satiate her ever-growing thirst. Revolution may be a great idea theoretically. According to Dickens, however, it just gets you too drunk too fast. Violence, folks, is not the answer.