The error, it seems to me, lies in the same confusion of distinct ideas, to which I had already occasion to advert. In ordinary language, we speak of the physical and moral nature of man, terming physical whatever relates to his material, and moral what relates to his immaterial being. Again, we speak of mind, and though in theory we consider it as a synonyme of soul, in practical application it has a very different signification. A person may cultivate his mind without benefiting his soul, and the term a superior mind, does not necessarily imply moral excellency. That mental qualifications or acquisitions are in no way connected with sound morality or true piety, I have pointed out before. Should any further illustrations be necessary, I might remark that the greatest monsters that blot the page of history, have been, for the most part, men of what are called superior minds, of great intellectual attainments. Indeed, wickedness is seldom very dangerous, unless joined to intellect, as the common sense of mankind has expressed in the adage that a fool is seldom a knave. We daily see men perverting the highest mental gifts to the basest purposes, a fact which ought to be carefully weighed by those who believe that education consists in the cultivation of the intellect only. I therefore consider the moral endowments of man as practically different from the mental or intellectual, at least in their manifestations, if not in their essence. To define my idea more clearly, let me attempt to explain the difference between what I term the moral and the intellectual nature of man. I am aware of the dangerous nature of the ground I am treading, but shall nevertheless make the attempt to show that it is in accordance with the spirit of religion to consider what in common parlance is called the moral attributes of man, and which would be better expressed by the word psychical, as divisible into two, the strictly moral, and the intellectual.
The former is what leads man to look beyond his earthly existence, and gives even the most brutish savage some vague idea of a Deity. I am making no rash or unfounded assertion when I declare, Mr. Locke's weighty opinion to the contrary notwithstanding, that no tribe has ever been discovered in which some notion of this kind, however rude, was wanting, and I consider it innate – a yearning, as it were, of the soul towards the regions to which it belongs. The feeling of religion is implanted in our breast; it is not a production of the intellect, and this the Christian church confirms when it declares that faith we owe to the grace of God.
Intellect is that faculty of soul by which it takes cognizance of, classes and compares the facts of the material world. As all perceptions are derived through the senses, it follows that upon the nicety of these its powers must in a great measure depend. The vigor and delicacy of the nerves, and the size and texture of the brain in which they all centre, form what we call native intellectual gifts. Hence, when the body is impaired, the mind suffers; "mens sana in corpore sano;" hence, a fever prostrates, and may forever destroy, the most powerful intellect; a glass of wine may dim and distort it. Here, then, is the grand distinction between soul and mind. The latter, human wickedness may annihilate; the former, man killeth not. I should wish to enter more fully upon this investigation, not new, indeed, in speculative science, yet new in the application I purpose to make of it, were it not for fear of wearying my reader, to whom my only apology can be, that the discussion is indispensable to the proper investigation of the moral and intellectual diversities of races. When I say moral diversities, I do not mean that man's moral endowments, strictly speaking, are unequal. This assertion I am not prepared to make, because – as religion is accessible and comprehensible to them all – it may be supposed that these are in all cases equal. But I mean that the manifestation of these moral endowments varies, owing to causes which I am now about to consider. I have said that the moral nature of man leads him to look beyond the confines of the material world. This, when not assisted by revelation, he attempts to do by means of his intellect. The intellect is, as it were, the visual organ by which the soul scans the abyss between the present and the future existence. According to the dimness or brightness of this mental eye, are his perceptions. If the intellectual capacity is weak, he is content with a grovelling conception of the Deity; if powerful, he erects an elaborate fabric of philosophical speculations. But, as the Almighty has decreed that human intellect, even in its sublimest flight, cannot soar to His presence; it follows that the most elaborate fabric of the philosopher is still a human fabric, that the most perfect human theology is still human, and hence – the necessity of revelation. This divine light, which His mercy has vouchsafed us, dispenses with, and eclipses, the feeble glimmerings of human intellect. It illumines as well the soul of the rude savage as of the learned theologian; of the illiterate as of the erudite. Nay, very often the former has the advantage, for the erudite philosopher is prone to think his own lamp all-sufficient. If it be objected that a highly cultivated mind, if directed to rightful purposes, will assist in gaining a nobler conception of the Deity, I shall not contradict, for in the study of His works, we learn still more to admire the Maker. But I insist that true piety can, and does exist without it, and let those who trust so much in their own powers beware lest they lean upon a broken staff.
The strictly moral attributes of man, therefore, those attributes which enable him to communicate with his Maker, are common – probably in equal degree – to all men, and to all races of men. But his communications with the external world depend on his physical conformation. The body is the connecting link between the spirit and the material world, and, by its intimate relations to both, specially adapted to be the means of communication between them. There seems to me nothing irrational or irreligious in the doctrine that, according to the perfectness of this means of communication, must be the intercourse between the two. A person with dull auditory organs can never appreciate music, and whatever his talents otherwise may be, can never become a Meyerbeer or a Mozart. Upon quickness of perception, power of analysis and combination, perseverance and endurance, depend our intellectual faculties, both in their degree and their kind; and are not they blunted or otherwise modified in a morbid state of the body? I consider it therefore established beyond dispute, that a certain general physical conformation is productive of corresponding mental characteristics. A human being, whom God has created with a negro's skull and general physique, can never equal one with a Newton's or a Humboldt's cranial development, though the soul of both is equally precious in the eyes of the Lord, and should be in the eyes of all his followers. There is no tendency to materialism in this idea; I have no sympathy with those who deny the existence of the soul, because they cannot find it under the scalpel, and I consider the body not the mental agent, but the servant, the tool.
It is true that science has not discovered, and perhaps never will discover, what physical differences correspond to the differences in individual minds. Phrenology, starting with brilliant promises, and bringing to the task powers of no mean order, has failed. But there is a vast difference between the characteristics by which we distinguish individuals of the same race, and those by which we distinguish races themselves. The former are not strictly – at least not immediately – hereditary, for the child most often differs from both parents in body and mind, because no two individuals, as no two leaves of one tree, are precisely alike. But, although every oak-leaf differs from its fellow, we know the leaf of the oak-tree from that of the beech, or every other; and, in the same manner, races are distinguished by peculiarities which are hereditary and permanent. Thus, every negro differs from every other