The consequences now enumerated, and the error from which they spring, are most frequently met with in the middle and higher classes of society. Aware that animal substances contain the largest proportion of nutriment in a given bulk, but ignorant of the relation subsisting between particular kinds of food and particular states of the system, and which in practice can never be safely overlooked, the fond parent naturally imagines that the more nutritious the food, and the larger the quantity administered, the stronger and healthier will the child become. No suspicion is entertained that strong diet may overpower weak organs, and thus induce the very evils which it is sought to avoid; whereas, by adapting the quality and quantity of the food to the condition of the system, the assimilating powers may be gradually invigorated, and healthy nutrition be completely ensured. Among the wealthier classes, imperfect nutrition most generally arises from excess in quantity, or a too stimulating quality, of food; but among the lower classes from deficiency in quantity or quality, added to scantiness of clothing, want of cleanliness, and imperfect ventilation. And hence Dr Clark, in treating of the prevention of scrofula and consumption in early life, lays great stress on the proper regulation of diet, and shews that, even in families free from all hereditary taint, a morbid condition of the system extremely favourable to the production of both diseases, is speedily brought about by continued mismanagement of diet; and both the public and the profession are deeply indebted to him for drawing attention to the extensive influence of dyspeptic ailments in paving the way for the future inroads of a deadlier disease. It is true that it has long been the fashion to ascribe all bodily and mental disorders to bile, indigestion, or the state of the bowels; but the rationale of the result has seldom been perceived, or turned to any good account in improving preventive or remedial treatment. Dr Clark’s treatise, however, presents a remarkable exception, and may be referred to as a most instructive specimen of cautious and discriminating medical inquiry.