Foucault's Pendulum

Umberto Eco’s second novel mines similar territory as The Name of the Rose (1980), but with even more esoteric references to secret knowledge and occult practices. I especially liked the way that Eco captures the more-radical-than-thou skepticism that secret knowledge adherents displayed when the emergence of Christianity would have seemed to have fully validated their claims: 

Someone had just arrived and declared himself the Son of God, the Son of God made flesh, to redeem the sins of the world. Was that a run-of-the-mill mystery? And he promised salvation to all: you only had to love your neighbor. Was that a trivial secret? And he bequeathed the idea that whoever uttered the right words at the right time could turn a chunk of bread and a half-glass of wine into the body and blood of the Son of God, and be nourished by it. Was that a paltry riddle? And then he led the Church fathers to ponder and proclaim that God was One and Triune and that the Spirit proceeded from the Father and the Son, but that the Son did not proceed from the Father and the Spirit. Was that some easy formula for hylics? And yet they, who now had salvation within their grasp — do-it-yourself salvation — turned deaf ears. Is that all there is to it? How trite. And they kept on scouring the Mediterranean in their boats, looking for a lost knowledge of which those thirty-denarii dogmas were but the superficial veil, the parable for the poor in spirit, the allusive hieroglyph, the wink of the eye at the pneumatics. The mystery of the Trinity? Too simple: there had to be more to it.

Recommended, especially if you enjoyed The Name of the Rose.