Jan met Spinoza as a child. The riots in the country had brought the philosopher to the Paviljoensgracht in The Hague, where he finds shelter in the mansion belonging to his father, the painter Hendrick van der Spyck. The little boy wins the trust and friendship of the philosopher, going to secret meetings in the Spinoza Circle, and witnessing the loneliness of free thought and some of the decisive episodes in the man's life at first hand. As an old man, Jan continues to look into the traces Spinoza's system has gradually left over time. There are those who claim to have seen him recently on the streets of Amsterdam, and he travels from there, despite his aversion to flying, to different parts of the world, stealthily detecting the presence of Spinoza. This novel is the story of that search.