Gaius Laelius
The metaphor of the "slippery slope" dates back at least to Cicero's essay "Laelius de Amicitia" (XII.41). The title character Gaius Laelius Sapiens uses the metaphor to describe the decline of the Republic upon the impending election of Gaius Gracchus: "Affairs soon move on, for they glide readily down the path of ruin when once they have taken a start."