insiti caloris spiritusque vitalis. In Book I, chapter 5 (1555) Vesalius calls the first of these nativus calor; Galen’s e)/mfuton qermo/n, this is the immortal substance of life endowed with intelligence and nourished by vital pneuma, the spiritus vitalis of the present phrase. Both of these play an important role in Galenic physiology, for which see May 1968, 50ff. The evolution of ancient, medieval, and Renaissance theories about pneuma or spiritus is traced in Verbeke 1945, Bono 1984, and Fattori and Bianchi 1984. The separate existence of animal spirit was denied in 1556 by Giovanni Argenterio De somno et vigilia Bk. 2 chaps. 7-10. See Siraisi 1990, 337–44.