It may be laid down, then, as a long-established axiom in regard to this subject, that men estimate the guilt of wrong belief in all matters relating to the welfare of mankind in exact proportion to the value of the interests involved, and to the opportunities enjoyed for obtaining information. Inasmuch as all our success and happiness depends upon our belief of the truth, we have two of the principles of reason and common sense to guide us. The first is, that we are to consider that to be right which has _the balance_ of evidence in its favor; and the second is, that nothing is to be assumed as true unless there is _some_ evidence that it is so. CHAPTER XX. CONSTITUTIONAL VARIETIES OF THE HUMAN MIND. In the preceding chapters have been presented the most important mental faculties which are common to the race. There are none of the powers and attributes of the mind as yet set forth which do not belong to every mind which is regarded as rational and complete. But, though all the race have these in common, yet we can not but observe an almost endless variety of human character, resulting from the diverse _proportions_ and _combinations_ of these several faculties. These constitutional differences may be noticed, first, in regard to the intellectual powers. Some minds are naturally predisposed to exercise the reasoning powers. Others, with precisely the same kind of culture, have little relish for this, and little power of appreciating an argument. In other cases, the imagination seems to be the predominating faculty. In other minds there seems to be an equal balance of faculties, so that no particular power predominates. Next we see the same variety in reference to the susceptibilities. In some minds, the desire for love and admiration is the predominating principle. In others, the love of power takes the lead. Some are eminently sympathizing. Others have a strong love of rectitude, or natural conscience. In some, the principle of justice predominates. In others, benevolence is the leading impulse. Finally, in regard to the power of volition, as has been before indicated, there are some that possess a strong will that is decisive and effective in regulating all specific volitions, while others possess various and humbler measures of this power. According to the science of Phrenology, some of these peculiarities of mind are indicated by the size and shape of different portions of the brain, and externally indicated on the skull. That these differences are constitutional, and not the result of education, is clear from the many facts showing that no degree of care or training will serve to efface these distinctive traits of the mind. To a certain degree they may be modified by education, and the equal balance of the faculties be promoted, but never to such a degree as to efface very marked peculiarities.