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"First, therefore we affirm, that this thin and spirituous matter, which is called the Animal Spirits, is the immediate Instrument of the Soul, in all her operations both of Sense and Motion."

— Power, Henry (1623-1668)

Author

Experimental Philosophy

Place of Publication

London

Publisher

Printed by T. Roycroft, for John Martin and James Allestry

Date

1664

Metaphor

"First, therefore we affirm, that this thin and spirituous matter, which is called the Animal Spirits, is the immediate Instrument of the Soul, in all her operations both of Sense and Motion."

Metaphor in Context

First, therefore we affirm, that this thin and spirituous matter, which is called the Animal Spirits, is the immediate Instrument of the Soul, in all her operations both of Sense and Motion. First, for sense, it is plain by what is discovered in a Vertigo; for the Brain it self is not of such a fluid substance, as to turn round, and make all objects to do so too; wherefore tis a sign that the immediate corporeal instrument of conveying the images of things, is the Spirits in the Brain. Secondly, That they are the chief Engine of Sight, is plain; not onely because the eye is full of these livid Spirits, but also because dimness of sight comes from deficiency of them, though the parts of the eye otherwayes be entire enough, as in sick and old persons, and in those troubled with an Amaurosis, or Gutta Serena. I had the last year a Patient, a young Boy of seventeen years old, who fell casually stark blind of his right eye; in which you could outwardly discover no fault at all (the Disease being an Amaurosis, or obstruction of the Optick Nerve) for, that Nerve being by successful means disobstructed and relaxed, so that the Animal Spirits were able to flow done to the Retina again, he shortly after perfectly recovered his sight again, without any relapse at all, to this present day. Thirdly, If you cast a Ligature upon any Nerve, you destroy both the sense and motion of that part whither that Nerve was propagated (as by that pleasant Experiment by tying the recurrent Nerves in a living Dogg, we have tryed) till by relaxing the Ligature the Spirits may have the freedome to channel into the Nerves again: Which truth is also handsomely made out, by that ordinary example of a mans Leg being asleep (as we call it) for by compression of the Nerves, the propagation of the Spirits into the part is hindred; for, as sense and motion is restored, you may feel something creep into the Leg, tingling and stinging like Pismires (as Spigelius compares it) which is the return of the Animal Spirits into that part again. Fourthly, That Spontaneous motion is performed by continuation of the Animal Spirits, from the common Sensorium to the Muscle, (which is the gross Engine of Motion) is sensibly evinced in dead Palsies, where one side is taken away. (pp. 67-69)