Disease and old age alone oppose obstacles to this proceeding; for by these causes the skull may be increased or diminished in volume, and it is generally irregular in thickness in old age: the _sutures_ also interrupt absolute parallelism, but their situation is known and allowed for, and the _frontal sinus_, or cavity at the top of the nose, in the frontal bone, (which is often enlarged and covered by the _schneiderian membrane_ giving great power to the nerves of smell) is so remotely connected that it can only affect a few organs,--five at the most. These few objections are so fully overruled by practice and observation, that they can never lead to error if the student exercise a proper degree of caution.--We may conclude then, that if men manifest their _true nature_ in their actions, (and men cannot always be dissemblers,) the mind influencing the brain, and thereby the skull, must present a developement corresponding to their real character--and that PHRENOLOGY or external examination leads to the results sought for when we examine human nature for the purpose of self improvement, or for moral and religious elevation of character. ON TEMPERAMENT. The Temperaments are commonly stated to be four only, and their sub-divisions; as these are united in the same individual. These are, the _Nervous, Sanguine, the Bilious, and the Lymphatic_; they are however rarely met with in a separate state, the greater number of persons presenting a mixed temperament, the most predominant of which are the _Sanguine-Bilious_ and the _Sanguine-Nervous_, a milder form of _Lymphatic and the Lymphatic_ with the _Sanguine, Bilious and Nervous_, may be stated as producing twelve varieties. Temperament may be defined as the natural constitutional tendency of the individual, producing a disposition to exert certain faculties more than others: for this reason they must be carefully studied, that their _active_ and _passive_ influence upon the mind may be ascertained. Their action is chiefly manifested in the _energy_ or _apathy_, of the individual's character; for when properly balanced, by their equal influence on a well cultivated mind, they produce the beautiful harmony of feeling, that leads to a right estimation of things whether moral, intellectual, or physical; by their combined influence in the physical man, that is on the passions and affections, or, on the intellectual being, that is, the perceptives actives, and the reflectives passive,--or upon the higher sentiments, when the moral energy is active, and the spiritual zeal passive,--they produce the noblest developement of character that can actuate human nature--the disunity of these produces but a heathen morality on the one hand, or religious fanaticism on the other: in the mind too, while there is an active _perception_ of facts, without due _reflection_ on causes, or the reverse of these, the mind may be led into an excess of its favourite pursuit, to the ultimate loss of much mental power.