English medieval and Renaissance literature, especially Shakespeare; Italian Quattrocento literature; Renaissance philosophy, especially the Platonism of Marsilio Ficino and Pico della Mirandola.
Selected Works:
The Platonism of Marsilio Ficino (1984)
Icastes: Marsilio Ficino's Interpretation of Plato's 'Sophist' (1989)
Nuptial Arithmetic: Marsilio Ficino's Commentary on the Fatal Number in Book VIII of Plato's 'Republic' (1994)
Plato's Third Eye: Studies in Marsilio Ficino's Metaphysics and its Sources (1995)
Synoptic Art: Marsilio Ficino on the History of Platonic Interpretation (1998).
Coauthored: Sources and Analogues of Old English Poetry: the Major Latin Texts (1976), and coedited Shakespeare's Plays in Quarto (1982) and Sir Philip Sidney's Achievements (1989).