Through steps such as these we can understand how it is, that as soon as some melancholy thought passes through the brain, there occurs a just perceptible drawing down of the corners of the mouth, or a slight raising up of the inner ends of the eyebrows, or both movements combined, and immediately afterwards a slight suffusion of tears. A thrill of nerve-force is transmitted along several habitual channels, and produces an effect on any point where the will has not acquired through long habit much power of interference. The above actions may be considered as rudimental vestiges of the screaming-fits, which are so frequent and prolonged during infancy. In this case, as well as in many others, the links are indeed wonderful which connect cause and effect in giving rise to various expressions on the human countenance; and they explain to us the meaning of certain movements, which we involuntarily and unconsciously perform, whenever certain transitory emotions pass through our minds. CHAPTER VIII. JOY, HIGH SPIRITS, LOVE, TENDER FEELINGS, DEVOTION. Laughter primarily the expression of joy—Ludicrous ideas—Movements of the features during laughter—Nature of the sound produced—The secretion of tears during loud laughter—Gradation from loud laughter to gentle smiling—High spirits—The expression of love—Tender feelings—Devotion. Joy, when intense, leads to various purposeless movements—to dancing about, clapping the hands, stamping, &c., and to loud laughter. Laughter seems primarily to be the expression of mere joy or happiness. We clearly see this in children at play, who are almost incessantly laughing. With young persons past childhood, when they are in high spirits, there is always much meaningless laughter. The laughter of the gods is described by Homer as “the exuberance of their celestial joy after their daily banquet.” A man smiles—and smiling, as we shall see, graduates into laughter—at meeting an old friend in the street, as he does at any trifling pleasure, such as smelling a sweet perfume.[801] Laura Bridgman, from her blindness and deafness, could not have acquired any expression through imitation, yet when a letter from a beloved friend was communicated to her by gesture-language, she “laughed and clapped her hands, and the colour mounted to her cheeks.” On other occasions she has been seen to stamp for joy.[802]