Among the fifteen kinds of change which we assumed, there were three of them (kinds one through three) whose existence is doubtful. We were unable to offer a definite opinion about them. Two other kinds (the eleventh and twelfth) depend on the increasing and decreasing of number, and these were considered to be respectival, and not in need of any further discussion.
Of the ten remaining kinds, two of them (the seventh and the thirteenth) are gradual changes, and must be taken up in the discussion of motion. However, the other eight kinds are instantaneous changes in which the potential existent is transformed into the actual existent instantaneously, without any temporal gap. The expression ‘generation and corruption’ is more or less used with regard to these changes. There is, however, some ambiguity about them which must be explained.
Therefore, this lesson is devoted to a discussion of these eight kinds of instantaneous change and applicability of the term ‘generation and corruption’ to them.
The expression ‘kawn’ in Arabic has the meaning of being, and in philosophical terminology it is used to mean coming about and is approximately synonymous to ‘huduth’ (newness, coming into existence in time), and the expression ‘fasad’ (corruption) is used as its opposite, meaning the destruction of a phenomenon. In this way, the term ‘generation’ is more specific than ‘existence,’ because it is not used for immutable existents.
These two expressions are usually used together, and a clear example of it is the sixth of the mentioned kinds of change, that is, the destruction of a part of a substantial existent and appearance of another part. However, it can be generalized to some other types. If an instance can be found for the third kind, the expressions generation and corruption may be applied there. Likewise, the succession of opposites (which is the tenth kind of change) can be considered generation and corruption in accidents, although this terminology is usually associated with substances.
However, the fourth kind, that is, the addition of a substantial part without the destruction of another part, can be called ‘generation without corruption.’ And the reverse may be said of the fifth type, that is, the destruction of a substantial part without the appearance of a part to replace it, can be called ‘corruption without generation.’
Likewise, the eighth kind, the appearance of new accidents, can be considered ‘generation without corruption’ and the ninth kind, the destruction of accidents, can be considered ‘corruption without generation.’
The attachment of the soul to the body can also be considered a kind of generation, in view of the fact that the attribute of life thereby appears in the body. The reverse, dying, can be considered a kind of corruption, in view of the fact that the life of the body is destroyed, though not in the sense that the spirit is destroyed, for the spirit is indestructible.
Whether or not generation without corruption can be imagined in types four and fourteen, and corruption without generation in types five and fifteen, hinges on whether the presence of two forms in a single matter is considered permissible and on whether it is held that the prior form remains when a new substantial form appears, and in the case of the destruction of a higher form, whether the lower form existed together with the higher form and continues.
If we hold that two forms cannot be present in a single thing, then we will be compelled to hold, in types four and fourteen, that the earlier form is destroyed, and in types five and fifteen that a new form is freshly brought about. In this case these types will also be considered types of generation and corruption, not as cases of mere generation and mere corruption.
Therefore, the problem which must be investigated is whether the presence of two forms in a single thing is permitted so that the assumption of the occurrence of two actual substantial forms in a potential existent and the continuation of one of them in an actual existent is allowed in cases five and fifteen, and the presence of two substantial forms in an actual existent and the persistence of the earlier form in types four and fourteen may be correct.
In types four and fourteen of the assumed types of change, the whole potential existent remains in the actual existent, and another substance is added as a new part to it, and a kind of union between them obtains, with this difference that in type four the form is incarnated in the matter, and the matter is the locus of this form. But in type fourteen, the soul is attached to the body, and the body is not considered its locus.
Now the question arises as to whether the form of the earlier existent vanishes and is corrupted and in place of it a more perfect form is brought about which possesses the perfections of the previous form, or in the new circumstances there really exist two forms, one of which is above the other vertically, not that the earlier form is destroyed.
For example, when a vegetable form comes into existence in a collection of elements, do these elements remain in the vegetable with their own actualities? Can it be said that in this plant oxygen, hydrogen, nitrogen, carbon, etc., actually exist, and that the vegetable form has become unified with the collection of them? Or should one say that the only form which exists in it is the vegetable form, and the mentioned elements exist only potentially?
Can it be said that when an animal soul attaches to specific materials, they preserve their specific existences and that they have actual existence within the animal existence, or should it be said that what has actuality is the form (soul) of the animal and that its body exists potentially? Do the materials which compose the human body and each of its millions of living cells have a specific form and actuality, and does the human soul attach to them as a higher form, or is that which is actual in a living human only his spirit, and does his body only exist potentially?
Likewise, in the case of the fifth and fifteenth types in which a part of the previous existent is destroyed or is separated from it, is it the case that from the beginning there were two substantial actualities and that later one of them leaves while the other remains with its previous actuality, or is it the case that at the beginning there exists a complete form, and with its detachment a less perfect form appears?
For example, when a plant withers and turns to dust, does the form of dust actually exist in the form of the plant and remain with that same actuality, or in the earlier circumstances was there only a complete vegetable form and with its passing does the form of dust newly appear?
Regarding the case of the detachment of the animal or human spirit from the animal or human body, do the materials actually exist previously, and after separation of the spirit do they remain with the same previous actuality, or in the previous circumstances is actuality restricted to the spirit and after its detachment new forms freshly appear?
Therefore, that which these discussions pivot upon regarding these types of change is whether the presence of two forms in a single existent is allowed or not. That is, if the presence of two forms in the later existent is allowed, types four and fourteen are considered to be a kind of generation without corruption, and if the presence of two forms in the earlier existent is allowed, then types five and fifteen will be considered cases of corruption without generation. However, if the presence of two forms is impossible, all of these types will be cases of generation and corruption.
Some philosophers do not allow the presence of two forms in a single thing and have reasoned that the form is the very actuality and thingness of a thing, and that the numerical identity of the form implies the numerical identity of the thing, while their unity is assumed.
This reasoning is unsatisfactory, for, firstly, the unity of a composite existent, as was indicated in Lesson Twenty-Nine, is an accidental unity because of the unity of the higher form, and, in fact, the composite existent is the existents which are somehow united with each other, not that they are really a single existent.
Secondly, the problem can be posed as follows: Is the presence of two forms in a single matter permissible or not, as noted in the title of the discussion. It is obvious that the real issues here cannot be resolved on the basis of terminology and language.
In any case, the question is whether the composing materials of vegetables, animals, and humans have an actual form other than vegetable form, and animal and human souls, or do the earlier materials lose their own forms and actualities when the vegetable form comes into existence in the previous materials, or the animal or human soul attaches to a body, and in technical terms, are their forms corrupted and do new forms come about for the materials after the death of a plant, animal or man, and its transformation into elemental materials?
It seems that there should not be any doubt that the earlier forms remain, and that the new forms come about vertically, and are somehow unified with them, and then after corruption or detachment the earlier actualities remain and no other new form appears for them.
This is confirmed by the fact that many elemental particles and organic and mineral materials are separately visible by optical devices, and billions of living existents, including white and red blood cells can be observed in man’s body, and they can be removed from the body and preserved under certain conditions, and hence, not only minerals and organic materials exist with their own actualities and specific forms within the existence of the vegetable, animal or human, but there also actually exist innumerable vegetable and animal existents within a higher animal or man. The animal and human spirit occurs as higher forms at a higher vertical level.
Is it acceptable to say that the bodies of man and animals have no actual existence apart from the existence of the spirit while the spirit is attached to the body and that when the animal or man dies and the spirit is separated from its body, the body obtains an actual existence and a new form appears in it?!
Therefore, there should be no doubt about the possibility of coexistence of two or more vertical forms in a single matter, for, indeed, this occurs frequently. That which is not possible is the coexistence of two contrary forms in a single matter which are in a horizontal position with respect to one another.
Here the question will be raised as to how one can distinguish vertical from horizontal forms.
The answer is that vertical and horizontal forms can only be distinguished by means of experience; that is, any form which experience proves to be incapable of coexisting with another form is horizontal, and any form which is capable of coexisting with another will be vertical.
Some examples of horizontal forms which are contrary to each other are the forms of water and steam and the forms of the various elements. However, the forms of the elements can coexist with vegetable, animal or human forms, and therefore they are considered to be vertical forms. Likewise, the lower forms of life, such as cells and corpuscles, can coexist with higher forms, such as the forms of higher animals and humans. For this reason, the forms of higher animals and of man are in a vertical relation to other forms.
Given this difference between forms, they can be divided into two groups: those forms which are successive, contrary to one another, and horizontal, and those which are superimposed or vertical. It is clear that this is a relative and relational division, and therefore it is possible for a form to be successive in relation to a certain form, but to be considered superimposing relative to another.
It is clear that generation and corruption is specific to instantaneous changes and motion is a feature of gradual changes. Therefore, in this respect one cannot include both of them in a single kind of change.
However, the absence of coexistence between generation and corruption and motion does not mean that there is no room for generation and corruption anywhere that motion exists. Rather it is possible for a moving thing to be characterized by generation or corruption from another angle.
To explain: it is possible for an existent to possess motion which ends in a single instant and at that very moment for another motion to appear in it. For example, the motion of an airplane which moves by the power of an engine is the effect of that power, and so, with the shutting down of that engine, the motion produced by it sooner or later comes to an end, and when a second engine starts working, another power is produced which causes a new motion for the plane.
Now, if it is supposed that the second motion begins the very moment that the first motion ends, although the motion of the plane is not interrupted there will actually be two motions, one of which is the effect of the power of the first engine and another which is the effect of the power of the second. Here, in addition to gradual change there is also an instantaneous change, which is the ending of the first motion and its transformation into the second motion. This change can be called generation and corruption.
Likewise, when two successive forms appear in a matter and one of them is corrupted and the other takes its place, the substantial motion of the earlier form ends, and at that very moment the substantial motion of the later form begins. This transformation of forms and succession of substantial motions also should be considered a kind of generation and corruption, for it is accomplished in one instant and without any temporal gap.
Therefore, the assumption of the continuation of motion in a single existent is compatible with the occurrence of generation and corruption in it, because it is in fact possible for two alternating motions to have occurred in it which superficially are considered to be a single motion.
The only case in which generation and corruption is incompatible with motion is under the assumption of a single real motion. If the material world possessed a single unitary existence and it were supposed that it had a single substantial motion, then there would be no room for generation or corruption. However, this assumption is not correct, as will be explained in the appropriate place.