Vorlesungen über Dynamik http://archive.org/details/cgjjacobisvorle00lottgoog [Lectures on Dynamics] (1842/3; publ. 1884).
Carl Gustav Jakob Jacobi: Frases em inglês
Vorlesungen über analytische Mechanik [Lectures on Analytical Mechanics] (1847/48; edited by Helmut Pulte in 1996).
Letter to Legendre (July 2, 1830) in response to Fourier's report to the Paris Academy Science that mathematics should be applied to the natural sciences, as quoted in Science (March 10, 1911) Vol. 33 https://books.google.com/books?id=4LU7AQAAMAAJ&pg=PA359, p.359, with additional citations and dates from H. Pieper, "Carl Gustav Jacob Jacobi," Mathematics in Berlin (2012) p.46
"Über Descartes Leben und seine Methode die Vernunft Richtig zu Leiten und die Wahrheit in den Wissenschaften zu Suchen," "About Descartes' Life and Method of Reason.." (Jan 3, 1846) C. G. J. Jacobi's Gesammelte werke Vol. 7 https://books.google.com/books?id=_09tAAAAMAAJ&pg=PA309 p.309, as quoted by Tobias Dantzig, Number: The Language of Science (1930).