 In these lectures and his published writings, Owen developed a reinterpretation of the significance of the Cuvier-Geoffroy dispute and brought it to bear on the issues of the historical development of forms. It is also in these lectures that Owen posed the theory of the archetypal vertebrate in his Hunterian lectures in 1845, a theme he elaborated in an important set of publications in 1847 and 1848. Employing aspects of William Whewell’s philosophy of science to develop these arguments, Owen expounded the theory of the unity of type in relation to Cuvierian form and function through the positing of an ideal archetypal form. This abstraction functioned for Owen both as a transcendental idealization similar to a Platonic form, and also as an immanent law working in matter, conceived on the analogy of a Newtonian law, which governed the development of forms in time (Sloan 2003; R. J. Richards 2002: chp. 14; Rupke 1993). By means of this theory, Owen claimed he could coherently explain both the deep resemblance of forms in their internal anatomy— the theme emphasized by Geoffroy St. Hilaire—, and also the close fitting of structure and function to the organism’s “conditions of existence”, the insight emphasized by Cuvier.