Pears takes Holmes' "science" of detection back to the origins of the scientific method, taking as his theme the nature of evidence itself, and exploring its scientific, theological and historical functions. The book's title is taken from Bacon's Novum Organum, the cornerstone of the Scientific Revolution, emphasising that philosophy literally points the way in this labyrinthine narrative of plot and counter-plot, where truth is shown to be a function of doctrine, and where each narrator worships his own Baconian "idol". Instead of retarding narrative progression, the extended metaphysical ruminations actually serve to map out the intellectual landscape of the period and demarcate the horizons of probability for each narrator's interpretation of events.
The novel is self-consciously learned and serious, yet there are moments of sly humour. While many passages might have been lifted from obscure theological treatises, light relief is offered by what could easily have come from yesterday's Daily Mail.
With pedant-defying scholarship it bludgeons the reader into accepting its authenticity by the very weight of historical detail. We take it on trust that our ancestors believed that "a pipe of tobacco every evening" was beneficial for consumptives, or that the procedures of alchemical method are being followed by the 17th-century equivalent of the forensic expert. On the whole, historical recreation is achieved with subtlety, providing "Diversion as well as Instruction". This is partly a consequence of thoughtful characterisation; for example, the first narrator is depicted as something of an innocent abroad, therefore his own exploration of the unfamiliar allows the backdrop of 17th-century Oxford to be erected unobtrusively. At times, however, this does start to read like the properties buyer's notes for the latest TV adaptation. For whom if not a potential director is the following nugget of information designed? "My bow to equals [was] perfectly executed , with just the right balance between the extended left leg, and the graciously elevated right arm." Such moments of historicist camp are rare, for in general each narrative rings true to both character and period, and thankfully refrains from the cod archaisms employed by some historical novelists.
This combination of erudition with ingenuity makes for satisfying reading. Particularly commendable is the fact that truth or common sense in the novel do not necessarily conform to modern beliefs or values. There are no Back to the Future-type leaps into knowledge, while the positive characters are not blessed with fully-formed liberal sensibilities. It is a testament to the author's skills as an historical novelist that one narrator is allowed to believe in unicorns, while another can exclaim "I must cut up a cat and see for myself" without losing either our trust or our sympathy.