Since the diseased states of the brain and spinal cord or of their membranes, which the preceding pathology discloses, exist, as is there shown, in all degrees of intensity, so the signs by which these states are denoted may vary from a prominence which it is impossible to overlook to an unobtrusiveness which it requires careful attention to discover. And from causes which we do not yet understand, the prominence of the sign is not always in accordance with the intensity of the state; but the important truth here maintained is, (and the more the practitioner observes, the more satisfied he will become that it is a truth,) that whenever these states exist in sufficient intensity to produce death, their presence may be discovered during life. It is not affirmed that these states can be distinguished one from another; but it is contended that the existence of some one or more of them may be ascertained with absolute certainty. As we sometimes see death occur, preceded by the ordinary symptoms of cerebral inflammation, when, on examination after death, nothing can be discerned but preternatural vascularity of the membranes or substance of the brain, without the presence of any inflammatory product that can be distinguished; and as, moreover, when _some_ inflammatory product is generated, we are in total ignorance of the laws by which, in one case, the blood-vessels pour out serum, in another secrete pus, in a third soften, and in a fourth indurate the cerebral substance; so the signs which indicate that these events have taken place are to us, at present, uncertain. There can be no question that the laws, according to which each of these events is produced, are fixed and invariable in their operation; and each may possibly be attended with its specific and therefore diagnostic sign; but it is certain that we have not yet discovered the one nor observed the other. And the preceding cases have been detailed under the heads assigned them, rather with the view of making the pathology clear, than in the hope from this arrangement of affording any guide to practice. In the mean time, what we may know, and ought to know, is when inflammation exists: what we may, in general, further know is, when some product of inflammation has been poured out still more to oppress the brain: to the thoughtful and discerning practitioner it would be without doubt a high satisfaction to be able to carry his diagnosis still further, and to ascertain _what_ that product is: the desire to arrive at such precise and perfect knowledge appears to me to be in the highest degree meritorious: the constant and unwearied endeavour to acquire it may not always succeed with reference to the particular object immediately pursued, but it cannot fail to increase his power and to strengthen his habit of observation; and the sure reward of a devotion thus truly honourable and faithful to the duties of his profession, if it should