The External and Internal senses

1. The External and Internal Senses
In philosophy, one of the fundamental functions of the human soul as conceived by the
peripatetic philosophers is the capacity to obtain knowledge by virtue of the external and internal
senses. This is generally known as the acquisition of knowledge which involves two different
processes: 1. Abstraction (tajrid) and 2. Perception (idrak). Both of them operate in a reciprocal
interaction between the knower, called object. In such a relation, the knower first abstracts the
image of an object in the external reality by means of the external senses of the soul, and the
perceives it as a form by means of its internal cognitive faculties or internal senses.
For Ibn Sina, there are two main groups of the faculties of the rational soul. The first group, called
external consist of five senses: touch (al-lams), taste (al-dhawq), smell (al-shamm), hearing
and sight (al-basar).
Touch is a faculty which is spread over the entire surface of the skin. It senses basically for diverse
circumstantial states: hot and cold, moist and dry. In additional, it also gives an impression about
the following light and heavy, smooth and rough, soft and hard.
Taste sense is located in the nerves spread out over the tongue. It perceives the taste through
the moisture that comes out of the squeezed juice.
Smell sense is a faculty which is located in the two lobes (za’idatayn) of the front part of the brain.
It perceives smells and odor by means of the air.
Hearing is a sense located in the nerves dispersed over the surface of the ear cavity. It perceives
the sounds by means of the air which enters the ear.
Sight is the faculty located in the nerves of the two pupils of the eyes. It perceives light and colors
as images imprinted on the humors of the eyes.
Ibn Sina also asserted that the five internal senses also consist of a hierarchy of five faculties,
such as: common sense (al-hiss al-mustarak), faculty of Imagination (al-khayaliyyah), faculty of
idea or thought (al-fikriyyah), faculty of discrimination/estimation (al-wahm), and retentive
faculty (al-hafizah). .
The first of these internal senses receives the information brought by the external senses and
combines and separate internal images or representation of the external sensible objects. It is
the common sense (al-hiss al mustarak).
Common sense resides in the forepart of the front ventricle of the brain. In other words, common
sense directly receives the data of the five external senses.
Al-Farabi described common sense and the ruling element of the external senses and as the
recipient of sensed forms, but is excluded from both the external and internal senses.

2. Suhrawardi asserts that common sense also visualizes the forms, even in dreams, in a direct a
visible manner without the interference of the imagination.
For ankaravi, common sense perceives the forms not only in wakefulness but also in sleep or in
dream by way of designation whereby the person who falls asleep can envision an individual form
away from its referent in external reality.
The second internal sense called representative faculty is situated in the back part of the
ventricle of the brain. This faculty retains the images representing the external objects when the
objects are no longer present to the external senses.
The third internal sense is estimative faculty or faculty of estimation that resides in the near part
of the middle ventricle of the brain. Is an internal sense which perceives and distinguishes things
not perceived by the other senses, such as the useful or hurtful.
The estimative faculty is an internal sense which perceives and distinguish things not perceived
by the other senses, such as the useful or hurtful.
The fourth internal sense, called the retentive and re-collective faculty (al-hjafizah and al-
dhakira), retains meanings and conserves these meanings.
The retentive faculty, also termed as memory and recollection, acts as a storehouse for
intentions and meanings transmitted from the estimative faculty and retrieves them when
needed.
The retentive faculty retains particular meanings and memorize them for close inspection and
appraisal by the perceiver for so long as they remain in it.
The fifth internal sense is the imaginative faculty (al-mutakhayyilah). The imaginative faculty is
situated in the middle ventricle of the brain near the vermin process. Its main task is to work on
the images and forms stored in the faculty of representation and thus separate and combine
them in various ways.