In order to clear up this question let us first examine the anatomical literature before Swedenborg’s time. And then we find that the Bartholins had already in a kind of way associated this branch of the soul’s activity with the cerebral cortex, because they supposed that the ›spiritus animalis›, (the ›spirits of life›), was contained in the cortex for the sensory functions, just as it was conserved in the medullary substance for the motor functions.[61]
And Thomas Willis considered that the ›spiritus animalis› was generated in the cerebral cortex, but afterwards underwent proper elaboration and distribution in the medulla of the cerebrum; and that the memory had its seat in the cerebral cortex.[62]
And Malpighi (1628-1694) had expressed the surmise, that the minute cortical elements, so particularly described by him, which correspond to what we now call the nerve-cells of the cortex, were small glands, ›glandulæ›, whose function was to prepare a substance which, conveyed through the nerves, calls forth perceptions.[63]
It had also been shown by the researches of Malpighi that these ›glandulæ› put forth a vessel-like fibre, which continued into the cerebral medulla; and that this medulla for the greater part consisted of such fibres or vessels.[64]
In how far these structures were ›fibres› or ›vessels›, and whether they proceeded from (›oriuntur›) or terminated in (›desinunt›) the small cortical elements, Malpighi leaves undecided. And when Boerhaave afterwards in his lectures on the brain describes these structures, he still depicts them as the finest tiny canals, which take up the ›spiritus animalis›, pressed into them from the cortex, and transport it down to the medulla oblongata, whence it is afterwards, by means of the nerves, distributed to the different parts of the body. This ›spiritus› Boerhaave describes as elaborated in the cortex, ›fabrica mirifica corticis praeparatus›.[65]
These observations and surmises have evidently exercised a great influence upon Swedenborg’s conception of the function of the cerebral cortex; but they alone could impossibly have aided him in reaching the enlightened standpoint at which he arrived. No, the most determining and decisive factor for him in this question evidently was a great mass of clinical and pathological observations which he had collected and synthesized, namely, symptoms of disturbances of consciousness and sensibility, which had been exhibited by such patients, who, as was shown by post mortem examination, had been injured in the cerebral cortex. And I shall later refer to some of these cases in connection with the consideration of the brain’s motor functions, because these patients nearly always also exhibited motor disturbances.
But even here I may quote some of Swedenborg’s own words, which will show what importance he attached to these testimonies: ›It is the cerebrum or the cortical substance in which the soul disposes and unfolds its purest and most simple organic forms of activity, and what the cerebrum is, appears from a change of the faculties in some diseases, as in apoplexy, epilepsy, paralysis, etc., likewise in many morbid states of the animal mind in a cerebrum wounded by various accidents;› (›The Brain›, No. 86).
And in another place he says: ›If the cerebrum is either inflamed or obstructed, or flaccid, or injured otherwise, the intellectual faculty is unsettled; as in paralysis, melancholy, in cases of delirium, in atrophy, apoplexy, in fevers, and other diseases; nay, the determination of the will also is similarly affected. For each single cortical substance contributes its share to this intellectory, that is, to this organ of the understanding, etc.› (›The Brain›, No. 104, r).
All these observations concerning the consequences of injury to the cerebral cortex—and the above-mentioned discoveries regarding the structure of the cerebral substance and the hypotheses concerning the relation of the cerebral cortex and cortical elements to the ›spiritus animalis› and the perceptions,—these clinical and anatomical experiences taken together seem to have led Swedenborg to the conviction that the activity of the soul and not least that just now in question, the sensory, had its seat in the cortex of the cerebrum.