The ‘Key to All Mythologies’ has become a byword for the mind-numbingly recondite and is typically thought of as a scene of arid and misguided pedantry. Readers of Middlemarch also gain a sense of the windy and unfocused emptiness of Casaubon's project, its seemingly unrealisable immensity bringing into relief the mythographer's pettiness. Casaubon did, of course, pay attention to detail – an excessive antiquarian attention to trifles indeed; but the logic of his bloated project led him to superimpose a universal pattern on immensely varied elements, regardless of their context or provenance. Mr Casaubon, readers soon divine, had bitten off more than he could chew.

Casaubon seems in that respect like one of the other central characters in Middlemarch, Dr Tertius Lydgate, who is engaged on a medical quest to unravel the scientific secrets of the most basic building block of life, what he calls ‘primitive tissue’. The supposed parallel here is obvious, for Lydgate, whose vainglorious dreams and ambitions exceed his grasp, is, under the influence of the French anatomist Marie-François Xavier Bichat (1771–1802), attempting to discover what might be called a key to all biology. Indeed, Lydgate, like Casaubon who desperately tries to reduce all myths to a common cipher, has a totalising and reductive approach to knowledge and is keen to unravel ‘the homogeneous origin of all the tissues’. Yet in both cases there are more generous ways of assessing each man's pretensions to learning, though Eliot, it seems, only grants such indulgence to Lydgate (who, to be fair, was also inspired – unlike the quietly misanthropic Casaubon – by philanthropic intentions to improve the lot of his fellow humans). As Eliot and her readers knew, Lydgate was onto something, and the knowing reader appreciates that despite being a young man in a hurry Lydgate was an unsung pioneer in the development of cell theory by Matthias Schleiden (1804–81) and Theodor Schwann (1810–82). The road, which for Lydgate proved to be a cul-de-sac, turned out to be a throughway. Sympathetic understanding of this sort is not extended to Casaubon or to his enterprise.