Rabanus Maurus's De rerum naturis

Select a book from the following list:
Preface 1		Preface 2
Book 1	Book 2	Book 3	Book 4
Book 5	Book 6	Book 7	Book 8
Book 9	Book 10	Book 11	Book 12
Book 13	Book 14	Book 15	Book 16
Book 17	Book 18	Book 19	Book 20
	Book 21	Book 22

Throughout the text numerical references between number signs (#) are to manuscript folios. When preceded by "M" these numbers refer to column numbers in volume 111 of the Patrologia Latina.