This is the first volume of a 1797 edition of the Encyclopaedia Britannica, a general-knowledge encyclopaedia arranged alphabetically. The Encyclopaedia was first published in three volumes in 1768, and it grew rapidly: this edition is in 18 volumes. The Encyclopaedia Britannica continues to be published today.

The pages shown here are part of the ‘Anatomy’ entry. The entry is over a hundred pages long, and contains a number of drawings. 

The Encyclopaedia and George Eliot's Middlemarch

In Book II of Middlemarch, George Eliot describes how the surgeon Lydgate came to discover his medical vocation. When he was a schoolboy, 

a wet day sent him to the small home library… he took down a dusty row of volumes with grey-paper backs and dingy labels – the volumes of an old Cyclopaedia… The page he opened on was under the head of Anatomy, and the first passage that drew his eyes was on the valves of the heart… he knew that valvae were folding-doors, and through this crevice came a sudden light startling him with his first vivid notion of finely adjusted mechanism in the human frame’ (Ch. XV) 

In that moment, Lydgate finds his ‘intellectual passion’.

In the following passage, Eliot argues that this ‘passion’ is no less important or interesting than romantic passion. She also hints at Lydgate’s fate, observing that often, a ‘catastrophe’ in a man’s professional and intellectual fortunes is ‘bound up’ with ‘the other [i.e. romantic] passion’.

Encyclopaedia Britannica on the Heart

Figure 4 of Plate XXV shows the heart of a foetus. The appearance and function of the heart are described on pp. 749-50.