The Doctor's medical essays, which are replete with humor, are written in defense of his special theory, the distinction between the active and the speculative mind. He thought there was too much science and too little intuitive sagacity in the world, and looked back longingly to the old-time common-sense, which he believed modern science had driven away. His own mind was anti-speculative, although he paid just tributes to philosophy and science and admired their achievements. He stigmatized the speculations of the day as the "lust of innovation." But the reader cares little for the opinions of Dr. Brown as arguments: his subject is of little consequence if he will but talk. By the charm of his story-telling these dead Scotch doctors are made to live again. The death-bed of Syme, for instance, is as pathetic as the wonderful paper on Thackeray's death; and to-day many a heart is sore for 'Pet Marjorie,' the ten-year-old child who died in Scotland almost a hundred years ago. As an essayist, Dr. Brown belongs to the followers of Addison and Charles Lamb, and he blends humor, pathos, and quiet hopefulness with a grave and earnest dignity. He delighted, not like Lamb "in the habitable parts of the earth," but in the lonely moorlands and pastoral hills, over which his silent, stalwart shepherds walked with swinging stride. He had a keen appreciation for anything he felt to be excellent: his usual question concerning a stranger, either in literature or life, was "Has he wecht, sir?"--quoting Dr. Chalmers; and when he wanted to give the highest praise, he said certain writing was "strong meat." He had a warm enthusiasm for the work of other literary men: an artist himself, he was quick to appreciate and seize upon the witty thing or the excellent thing wherever he found it, and he was eager to share his pleasure with the whole world. He reintroduced to the public Henry Vaughn, the quaint seventeenth-century poet; he wrote a sympathetic memoir of Arthur Hallam; he imported 'Modern Painters,' and enlightened Edinburgh as to its merits. His art papers were what Walter Pater would call "appreciations,"--that is to say, he dwelt upon the beauties of what he described rather than upon the defects. What he did not admire he left alone.