Far, too far, from having answered all the demands of composition, my limits force me, and my subject requires, to give a faint sketch of the most prominent features of Expression, its assistant and interpreter. They interweave themselves so closely with each other, and both with Invention, that we can scarcely conceive one without supposing the presence of the rest, and applying the principles of each to all; still they are separate powers, and may be possessed singly. The figure of Christ by M. Agnolo in the Minerva, embracing his cross and the instruments of suffering, is sublimely conceived, powerfully arranged; but neither his features nor expression are those of Christ. Expression is the vivid image of the passion that affects the mind; its language, and the portrait of its situation. It animates the features, attitudes, and gestures, which Invention selected, and Composition arranged; its principles, like theirs, are simplicity, propriety, and energy. It is important to distinguish the materials and the spirit of expression. To give this we must be masters of the forms and of the hues that embody it. Without truth of line no true expression is possible; and the passions, whose inward energy stamped form on feature, equally reside, fluctuate, flash or lower on it in colour, and give it energy by light and shade. To make a face speak clearly and with propriety, it must not only be well constructed, but have its own exclusive character. Though the element of the passions be the same in all, they neither speak in all with equal energy, nor are circumscribed by equal limits. Though joy be joy, and anger anger, the joy of the sanguine is not that of the phlegmatic, nor the anger of the melancholy that of the fiery character; and the discriminations established by complexion are equally conspicuous in those of climate, habit, education, and rank. Expression has its classes. Decebalus and Syphax, though both determined to die, meet death with eye as different as hues. The tremulous emotion of Hector's breast when he approaches Ajax, is not the palpitation of Paris when he discovers Menelaus; the frown of the Hercynian Phantom may repress the ardour, but cannot subdue the dignity of Drusus; the fear of Marius cannot sink to the panic of the Cimber, who drops the dagger at entering his prison, nor the astonishment of Hamlet degenerate into the fright of vulgar fear.