Chapter 3: Jacob Schegk on the Plastic Faculty

[the following is a chapter summary of Medical Humanism by Hiro Hirai; feedbacks are welcome; all the quotations are from quotations in the book]

Jacob Schegk (1511-1587) advanced the theory of the plastic faculty, which imposed much influence upon later thinkers such as Daniel Sennert, William Harvey and even Leibniz. What this plastic faculty is will be the main enquiry of this chapter. In this summary, I will follow Hirai’s paper structure and proceed by dividing Schegk’s work On the Plastic Faculty of the Seed into three parts, and review 1) what the plastic faculty is, 2) how it works in fetal formation and 3) its identification with intellect.

1. What is a Plastic Faculty?

Following Aristotle, Schegk articulates that the term sperm is not the material cause

but the efficient cause of the formation of animal body. In other words, this term sperm, does not refer to the material liquid but a certain reason-principle, which he calls the plastic faculty. The efficient cause is further divided into two parts – one is the principal efficient cause, i.e. the agent in actuality, as in the male parent or the heaven, while the other is instrumental, which is this plastic faculty. We know that the male parent is, being actuality, animate and corporeal, and this faculty or the sperm cannot be animate and corporeal because then, its ontological status is identical with that of the parent, and is no longer identified as instrumental but principal. But it cannot be inanimate either, because what is totally inanimate cannot produce what is animate, the latter being nobler than the former. This leads Schegk to offer a third option, that is to say, this spermatic faculty is neither animate nor inanimate, but rather it is non-animate. What does this mean? This non-animatedness, Schegk explains, is likened to “a logos and a certain entelecheia of an organic body.”

In this way, Schegk makes a distinction between an animated body and a non-animate principle endowed with, what he calls, a productive potentiality. It is potentiality because it is subordinated to another principal agent, and it is productive because it is active whole remaining in potentiality. But how is it possible? Since for Aristotle, matter is a pure potentiality, and it is pure potentiality because it is inert. Schegk argues that something productive separates from the principal agent and acts as an instrumental agent (hence, not actuality but potentiality) but it itself is not inert since it is endowed with a reason, forming principle (hence, not pure potentiality butproductive potentiality). He also equates this productive potentiality with the substantial form of natural things.

Schegk continues to define what this reason-principle means. According to Schegk, Galen recognized that there is some rational in the works of nature, but not wanting to attribute intelligence to all things, Galen gave up an idea of nature as a rational principle. But Schegk tries to find a way to reconcile this apparent dilemma by arguing that there must be a non-intellectual reason-principle in nature, since without such a principle, we cannot explain why nature is regarded as rationally ordered. Here, Schegk is quick to recognize also that the works of nature are different from those of art, because the reason-principles of art are external efficient causes, i.e. artificer, while the reason-principle of nature is internal efficient causes, i.e. the spermatic faculty.

2) How does it do what it does?

The spermatic faculty is conceived as a non-animate instrumental efficient cause, and since only what is animate can produce what is animate, this faculty needs a principal cause to assist it in order to get the generation across. In generation of natural things, the principal efficient cause, i.e. the male parent, exists already in actuality. This agent cannot transmit its own essence to the offspring, because then the offspring would become identical with the parent. What the principal efficient cause does is to transmit the actuality of its existence without sending the essence of itself. And this actuality without the essence is what Schegk calls the second actuality, or the productive actuality. How does it work? What on earth is the second actuality, anyway? Heere, Schegk calls attention to the very useful analogy of perceiving visible things. When we see an apple, for instance, the species/essence of the apple stimulates our vision through its actuality, Schegk tells us, while the species itself remains in its body. So, the apple does not send its essence to us – or else, we will have another apple in our mind in actuality! But its essence only stimulates us, activating our receptivity for the actuality derived from it in our mind. This second actuality is separable from the agent and, Schegk argues, it is our fantasia that makes this reception possible. This second actuality in the seed is what is called the productive actuality, whose ontological status is intermediate between what is animate and what is to be animated, according to Schegk. This is further linked to the psychic and substantial principle, which generates a substance, i.e. the soul.

So, this productive actuality (the second actuality derived from the principal cause) is communicated through this spermatic faculty, i.e. the productive potentiality. Again, it is productive potentiality because it assists the actuality to be communicated to the offspring. And just as the soul of the heaven is corporeal while it is immaterial, this active principle too is corporeal as its principal efficient cause is an animate body in actuality. Like the celestial soul, the productive actuality does not have a substantial matter, hence it is immaterial, but because it animates the body, it must share corporeity with the body it animates. Further, it must be inseparable form a body in order to perform its actions. But the second actuality itself lacks its body as it is only communicated through the body. So, what happens is that when ① the principal efficient cause dispatches in ② the spermatic faculty (i.e. productive potentiality) the second actuality (i.e. productive actuality), ③ the second actuality is tied to and has never left a body, though it gets transmitted from one body to another, for the spermatic faculty is potentiality, i.e. corporeity without materiality, and in this way the spermatic faculty is essential in generation and formation of fetuses since it acts as a vehicle for the second actuality (i.e. the form) to get to the pure potentiality (i.e. the matter). It is in this way that Schegk calls the spermatic/plastic faculty a divine body (corpus divinum).

① The principal efficient cause => ② the second actuality in the instrumental efficient cause => ③ the second actuality gets communicated to the material cause.

This status of having a divine body marks the distinction between the spermatic faculty and the intelligence, which is wholly devoid of matter or corporeity. In sum, this spermatic faculty is different from the celestial element, and this is why Aristotle did not identify this divine body with the celestial element but only said that this divine body is only analogous to the element of the stars. Hence, this spiritual vehicle of the plastic faculty stands between the soul and nature in the ontological hierarchy. Such a spiritual body is called a vital faculty, and is identified as the life-giving heat contained in the seeds and in the residue of animals. It seems that the plastic faculty, spermatic faculty, divine body, spiritual body and vital faculty are all the same thing with different names. This faculty needs a vehicle as its manifestation because the formative energeia, i.e. the second actuality, cannot alone wield its power without an intermediate body.

1. Intellect and the Human Soul

In this way, the difference between the intellect and the spermatic faculty has been established – the former is without materiality or corporeity but the latter is without materiality and is corporeal. This leads Schegk to say that the only human soul is separable from matter and all the other souls are generated in the proper sense of the term, that is, drawn from the potentiality of matter by the plastic faculty with the help of its spiritual vehicle which itself is inseparable from matter. So when the soul enters the body in order to animate it, the plastic faculty disappears and is replaced by the soul completely. The plastic faculty as the instrumental efficient cause gets replaced by the former cause proper, i.e. the soul, which remains in the spiritual body. And the human soul, as Schegk tells us, “is not drawn from the potentiality of matter by the plastic logos but is introduced into matter thanks to the intellect’s divine and immortal essence, which may be created but not generated.” So the human soul is consubstantial to this spiritual, divine body, and once the plastic faculty generates the organic body, the soul begins to vivify and the preserve the formed body.

To recap:

• The principal formal cause and the actuality= the male parent

• The instrumental formal cause = the spermatic faculty, formative power, plastic faculty, divine body, spiritual body

  • Productive potentiality, because it assists the actuality to get communicated to the matter

• The second actuality = the movement derived from the male parent

  • Productive actuality, because it is without the substantial matter yet but is a pure movement transmitted from the first actuality, i.e. male parent

• Human soul = preexists and is introduced into the fetus once the second actuality is communicated to the matter; it also replaces the spermatic faculty.

• Intellect = celestial element and the human soul; not equivalent with the plastic faculty or the second actuality, which is corporeal without being material.

Schegk quoted in Hiro Hirai, Medical Humanism, 84-85.

Schegk quoted in Hiro Hiral, Medical Humanism, 92-93. “This body [the spermatic/plastic faculty] differs from the celestial element because it evidently has no nature separable from its matter nor from seminal liquid. Because of this, Aristotle says that it is not celestial but similar by analogy to the celestial [element], or ‘analogous to the higher element.’ This body penetrates all matter, forming and figuring it, and distinguishes it by the natures of its parts […]. Indeed, this body is totally spiritual and most akin to the substance of the plastic logos. It is established that this [logos] is a certain energeia of the first actuality and, so to speak, the second yet substantial actuality of another animate and physical body. But [the body of the plastic logos] is evidently itself not a physical body. For otherwise, a physical body cannot enter and penetrates its matter because there is no [mutual] penetration of physical bodies.”

Ibid., 99.