Medical Science and the Anatomia Animata in Milton's Paradise Lost

ody is ‘discerpible’, or divisible, spirit must be, in contrast, be indivisible and elastic. 94
As in the religious and medical models, spirit is the active force, body is inert, yet oddly
intractable in its impenetrability.
Glisson too, shows himself to be well acquainted with the iridescent signifying
of the word spirit but, unlike More, he embraces the new chymical definition. From his
earlier, animistic images of the spirits’ activities in the body, comes a more
scientifically nuanced version of active substance. In Anatomia hepatis he shows that
his professional usage of the word draws meanings from his early training in classics
through to his later interest in chymistry. Giglioni translates thus:
“The word spirit”, Glisson writes, “insofar as it is attributed to the
bodies, has different meanings”. It can generically refer to any kind of
body which has been rarefied to the point of becoming volatile (in this
respect “wind, air, breath and exhalations in general” were rightly
viewed by the ancient authors as sorts of spirit). It can also mean “any
body that is subtle, active, and very penetrating”. Finally spirit can
also mean “that element which, after a due process of fermentation,
but not before, strives upwards spontaneously, and becomes volatile”.
This is “the most precise meaning of the word spirit, in that it is
understood as an elementary part of a compound. The chemists call it
mercury”. 95
Carefully beginning by locating his work as natural philosophy, Glisson gives a set of
definitions that shows how, even when clearly demarcated from theological concerns,
the term, like the body it describes, is subtle, active and penetrating. Glisson does not
define spirit in terms of a binary opposition to body or matter. The natural world is full
of spirituous breath; the classical definitions are included, but, unlike Henry More’s
account, Glisson’s spirit also validates the newest domain of medical theory with its
chymical definition.
It is, as we shall see, this expansion into the realm of the chymistry of
interacting elements that enables Glisson to develop his conception of living,
perceptive, motivated matter. The formulation of his system of vitalist natural
philosophy came to its peak in his late tract De Natura Substantiae Energetica,
94 More makes this definition of ‘discerpible’ early in his Immortality of the Soul: “By Actuall Divisibility
I understand Discerpibility, gross tearing or cutting one part from another. These are immediate properties
of Matter” (12-13). Milton’s angels are not quite what More would call ‘indiscerpible’ as they do get
wounded in the account of the war in heaven, although angelic substance heals without the suffering of
human flesh; angelic substance is also capable of becoming less rarefied and grosser with repeated sin.
95 Glisson quoted in Giglioni, ‘Genesis of Francis Glisson’s Philosophy of Life’, 124.
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