This riddle is concocted from Section 30 of Francis Bacon's strange book of physiological investigation, Sylva Sylvarum, or a Natural History in Ten Centuries (1626). My reason for posing it includes but goes well beyond piquing curiosity about what follows in this chapter, because responding to its conjunction of terms, puzzling through to the answer, draws us deep into early modern habits of bodily thought and sensation at a time-just before Harvey's discovery of the circulation of the blood in 1628-when those habits were under challenge. In Section 30, entitled "Experiment Solitary touching the Commixture of Flame and Aire, and the great Force thero£:' Bacon meditates upon the properties of fire and air in an attempt at scientific explanation of various kinds of force. (We should understand "force" here to mean the explosion, under compression, of air and fire.) For Bacon, human motion is one form of elemental explosion; indeed, in sudden or concentrated displays of force and velocity by the human body, he finds the combination of air and fire most beautifully expressed. l But it is
Bacon's terms of human motion that make his meditation seem so unfamiliar to modern readers because he discovers categorical affinities, where we would not, between the properties and characteristic behaviors of unlike bodies.