The mammillary bodies are two small ball-shaped structures that lie right next to one another just anterior to the midbrain; hence Two peas in a pod that lie side by side. They are part of the diencephalon, which comes from the Greek Dia, meaning between/across, and enkephalos, meaning brain. Thus, the diencephalon means across-brain or between-brain. The mammillary bodies are commonly affected by alcoholism, and subsequent thiamine deficiency can result in Wernicke’s encephalopathy, which is characterized by ophthalmoparesis and ataxia, which can progress, albeit rarely, to the irreversible stage of Korsakov psychosis, which is characterized by anterograde amnesia and confabulation. Hence With pints come lies and paralyzed eyes, And sideways you will lean.