Man would be utterly unfit for the sphere that he occupies, if he had not the opposite capacities required by innumerable opposite conditions. Physiologically, he requires calorific powers to fit him for cold climates, and cooling capacities to fit him for the torrid zone. Morally, he requires warlike powers to meet enemies and dangers, as well as affections for the sphere of domestic love. He requires the conscious intellect to call forth and guide his powers in exertion, and a faculty for repose and recuperation in sleep. He requires self respect to sustain him in elevated positions, and humility to fit him for humble duties and positions. We can conceive no faculty which has not its opposite,--no faculty which would not terminate its own operation, like a flexor muscle, if there were no antagonist. Benevolence would exhaust the purse and be unable to give, if Acquisitiveness did not replenish it; and Avarice unrestrained would lose all financial capacity in the sordid stupidity of the miser. Each faculty alone, without its antagonist, carries us to a helpless extreme. The antagonism of faculties is so self evident a law of nature that if Dr. Gall had pre-arranged a psychic philosophy in his mind, instead of being a simple observer of facts, he might have given a very different aspect to the science. But he arranged no psychic philosophy, and he did not carry his observations far enough to lead him into the law of antagonism, and hence left a rude system, lacking in the symmetry and completeness necessary to give it the position of a complete philosophy. But while the law of antagonism should control our psychic studies, it is not always convenient to express this antagonism in our nomenclature, or to group the functions of all regions of the brain in such a manner that each group or organ shall exactly correspond to an antagonism in another organ; for in expressing the functions of parts of the brain we are limited by the structure of the English language, and have to make such groups as will be conveniently expressed by familiar English words,--the words of a language that has grown up in a confused manner, and was not organized to express the faculties of sub-divisions of the brain. Hence, for want of a pre-arranged language, with words of accurate definition and exact antagonism, we can only approximate a perfect nomenclature, and must rely more upon description than upon classification and technical terms.