Now and then his wit is very brilliant, lighting up its surroundings like the sudden appearance of a meteor. The essence of humor consists in a contrast which places the object or person compared at a disadvantage. If the contrast is a dignified one we have high comedy; but if the reverse, low comedy. Some of Holmes's comparisons make the reader laugh out aloud. He says that a tedious preacher or lecturer, with an alert listener in the audience, resembles a crow followed by a king-bird,--a spectacle which of itself is enough to make one smile; and as for an elevated comparison, what could be more so, unless we were to seek one in the moon. There is a threefold wit in it; but the full force of this can only be appreciated in the original text. Nature commonly sets her own stamp on the face of a humorist. The long pointed nose of Cervantes is indicative of immeasurable fun, and there have been many similar noses on the faces of less distinguished wits. Doctor Holmes ridiculed phrenology as an attempt to estimate the money in a safe by the knobs on the outside, but he evidently was a believer in physiognomy, and he exemplified this in his own case. His face had a comical expression from boyhood; its profile reminded one of those prehistoric images which Di Cesnola brought from Cyprus. As if he were conscious of this he asserted his dignity in a more decided manner than a man usually does who is confident of the respect of those about him. Thus he acquired a style of his own, different from that of any other person in Boston. He was not a man to be treated with disrespect or undue familiarity. A medical student named Holyoke once had occasion to call on him, and as soon as he had introduced himself Doctor Holmes said: "There, me friend, stand there and let me take an observation of you." He then fetched an old book from his library which contained a portrait of Holyoke's grandfather, who had also been a physician. He compared the two faces, saying: "Forehead much the same; nose not so full; mouth rather more feminine; chin not quite so strong; but on the whole a very good likeness, and I have no doubt you will make an excellent doctor." After Holyoke had explained his business Doctor Holmes finally said: "I liked your grandfather, and shall always be glad to see you here."