Jacques-Louis David, Oath of the Horatii, 1784. High quality image on the Louvre website.
Karl Friedrich Schinkel, Gothic Church on a Rock by the Sea, 1815. High quality image and short essay at the Google Cultural Institute.
Eugène Delacroix, Liberty Leading the People, 1830. High quality images (including details) on the Louvre website.
Below are links to primary sources in translation on Google Books and other archival sites. Although good starting points for research and discussion, it is best to find a modern translation if you plan to study the work closely or cite it in a paper.
Jean-Jacques Rousseau, Confessions, 1769 (Vol. 1, Vol. 2). Edmond Hédouin's 1896 English translation via Google Books. See "Further Reading" below for a link to Angela Scholar's 2000 translation via Worldcat.
William Wordsworth, Lyrical Ballads, 1800 (Vol. 1, Vol. 2). First edition on Google Books. See "Further Reading" below for a link to a modern edition.
François-René de Chateaubriand, Genius of Christianity. 1802 Transcription of an 1871 English translation. Of particular interest are pages 370-5, "Of the Influence of Christianity on Music."
Giuseppe Mazzini, Philosophy of Music, 1836. 1891 translation on Google Books (begins on page 1).
Schumann, Dichterliebe:
Berlioz, "Symphonie fantastique":
Romanticism: Heilbrunn Timeline of Art History. Essay and slide show on Romanticism in visual art on the website of the Metropolitan Museum of Art. Includes links to other related essays on the Met site.
Online resource containing substantial essays on philosophical heavyweights. Good place to start for a research project on music and aesthetics. Bibliographies of secondary literature are included for each entry.
Broad Topics
18th Century German Aesthetics (includes Winckelmann, Lessing)
18th Century French Aesthetics (incl. Rousseau)
Individuals
Links to Worldcat entries except where specified.
Abrams, M. H. The Mirror and the Lamp: Romantic Theory and the Critical Tradition. Oxford and New York: Oxford University Press, 1971.
Breckman, Warren. European Romanticism: A Brief History with Documents. New York: Bedford/St. Martin’s, 2008.
Charlton, David, ed. E. T. A. Hoffmann’s Musical Writings: Kreisleriana, The Poet and the Composer, Music Criticism, Martyn Clarke, trans. Cambridge and New York: Cambridge University Press, 1989.
Daverio, John. Nineteenth-Century Music and German Romantic Ideology. New York: Schirmer, 1993.
Ferber, Michael, ed. A Companion to European Romanticism. Oxford: Blackwell Publishing, 2005.
Ferber, Michael. Romanticism: A Very Short Introduction. New York and Oxford: Oxford University Press, 2010.
Hoffmann, E. T. A., Tales of E .T. A. Hoffmann, Leonard Kent and Elizabeth Knight, eds. and trans. Chicago and London: University of Chicago Press, 1969.
Honour, Hugh. Romanticism. New York: Westview Press, 1979.
Le Huray, Peter, and James Day. Music and Aesthetics in the Eighteenth and Early-Nineteenth Centuries, abridged ed. Cambridge and New York: Cambridge University Press, 1988.
Nisbet, H. B., ed. German Aesthetic and Literary Criticism: Winckelmann, Lessing, Hamann, Herder, Schiller, and Goethe. Cambridge and New York: Cambridge University Press, 1985.
Rosen, Charles. The Romantic Generation. Cambridge, MA: Harvard University Press, 1995.
Rousseau, Jean-Jacques. Confessions, Angela Scholar, trans. Oxford and New York: Oxford University Press, 2000.
Schlegel, Friedrich. Philosophical Fragments, Peter Firchow, trans. Minneapolis: University of Minnesota Press, 1991.
Schopenhauer, Arthur. The World as Will and Representation, 2 vols., E. F. J. Payne, trans. New York: Dover, 1969.
Kathleen, Wheeler M., ed. German Aesthetic and Literary Criticism: The Romantic Ironists and Goethe. Cambridge and New York: Cambridge University Press, 1984.
Wordsworth, William, and Samuel Taylor Coleridge. Lyrical Ballads and Other Poems, Martin Scofield, ed. Ware: Wordsworth Editions Ltd., 2003.