Superphysics Superphysics
Section 1

Two Kinds of Motion: Inherent and Non-inherent

by Avicenna
3 minutes  • 629 words
Table of contents

It is wise to describe something before proceeding to establish its reality of existence*.

*Reality of existence; or its whereabouts. Doctor S. Landauer thinks that the word ayniyyat in the text must be wrong, because nowhere throughout this section is the «Whereabout» of the mental powers so much as hinted at; whereas the burden of the whole chapter is to prove merely that such powers do exist, i.e., their inniyyat, which is a word used by Arab Logicians.

Therefore, we should first establish the existence of the spiritual powers, before we define each one of those powers, and then enlarge on it.

The most peculiar characteristics of spiritual properties are 2:

  1. Setting in Motion (Impulsion)
  2. Perception

We will show show that there is a moving cause to every moving body.

Examples of natural motions are:

  • the sinking of the heavy
  • the rising of the light

Bodies moving in motions over and above the natural motions have moving* causes, which we call souls or spiritual powers.

*Translator’s Note: Ibn Sînâ has a clear premonition of Newton’s Theory of Gravitation 700 years earlier than Newton

Any body, from the time that it is perceptible, is perceptible not because of the body.

Some of perceptible bodies share something in common, but differ in an other things. That which is shared in common is other than that in which they differ.

The mind that encounters all bodies will perceive them having this in common: that they are bodies.

Afterwards, it perceives them as differing in how they move in different ways.

This is why the following concepts exist:

  • a body at rest
  • a body at motion

Without such perception of motion, the only concept possible would be motion along a circle. This is because it will see motion in a straight line as a series of starts and stops.

Hence, bodies are not to be clothed with the attribute of motion because they are bodies. Instead, they have motion because those motions come from above and beyond their corporeity.

This is similar to footprints being mere effects from the walker.

The bodies generated from the Four Elements of earth, air, fire, water have motions which come, not from constraint, but from 2 kinds of motion:

  1. Motion inherent in the decree of its element

by reason of the supremacy over it of the power of one of its constituents, and thus decreeing its motion towards the position in space naturally appointed for it

An example is a man moving downwards by the nature of the preponderating[8] heavy element in his body.

This kind of the motion of bodies takes place only in one direction and with a constant tendency.

  1. Motion that goes against the decree of its element

This decree is to rest in the natural position as soon as it reaches that position.

Examples are:

  • a man’s moving his body along the Earth’s surface
  • a flying bird’s motion with its heavy body high up through the sky

Thus, the 2 motions have 2 accounting causes. They are different one from the other:

  • one is “Natural”
  • the other is called “Soul” or “Spiritual Faculty”.

These motions then affirm the existence of spiritual faculties.

Whereas, in respect of Perception, because that


  • are bodies
  • can be perceived repeatedly

Perception will not ever differ from bodies through difference of their substance, but by certain powers or faculties borne within those bodies.

We will demonstrate these spiritual faculties.


[A]A Why and Wherefore moving it. Note the difference between sabab and illah. Transcriber addition: sabab (سبب) and illat (علّة): Sabab means the general conditions that are conducive to something occuring, whereas illat is the reason in cause-and-effect. Traditionally, illat is used in logic or medicine, whereas sabab would be more likely to be heard in common speech.

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