Opus Majus of Roger Bacon, Vol. II (Burke English trans.)

There must then for this reason be two kinds of senses: one containing the special senses, the common sense, and the imagination, which are influenced by the first class of qualities; and the other containing the estimative faculty and memory, which are referred to the second class of qualities. But the cogitative faculty, owing to the excellence of its functions as compared with other faculties, is distinguished from them. In the generally accepted translation of Aristotle the whole faculty is called memory, which has the power of retaining forms; and therefore not only the storehouse of the common sense, but also that of the estimative faculty, is called memory. Therefore what is here called imagination is comprehended under memory in the translation of Aristotle that is in common use. But without doubt memory must be a double faculty with two quite distinct parts, so that one shall be the storehouse of the common sense and the other that of the estimative faculty; and these will differ in species, subject, organ, and operation. Moreover, although these faculties have been placed in the brain, we must understand that the marrow-like substance of the brain is not itself sensitive, as Avicenna teaches in the tenth book On Animals, respectfully correcting Aristotle on this point.

For the marrow in other parts of the body is not sensitive, and therefore it is not so here. But it is the container and storehouse of the sensitive faculties, containing slender nerves in which sense and sensible forms are located. But in order that all doubt may be removed, we must consider that the sensitive soul has a twofold organ or subject; one is basic and the seat of life, namely, the heart, according to Aristotle and Avicenna in the books On Animals; the other is that which is first changed by the forms of qualities, and in which the operations of the senses are more manifest and distinguished, namely, the brain. For if the head is injured, an evident injury is suffered by the sensitive faculties, and an injury to the head is more evident to us than one to the heart, and frequently occurs. For this reason, in accordance with the more obvious consideration, we place the sensitive faculties in the head; and this is the opinion of physicians who do not think that the origin of the faculties...