De Umbris Idearum (Latin for "On the Shadows of Ideas") is a book written in 1582 by Italian Dominican friar and cosmological theorist Giordano Bruno. In this book, he proposes a system integrating mnemonics, Ficinian psychology, and hermetic magic. It is the first book he wrote covering the subject of memory, a topic on which he would focus the rest of his works.^[1]

• Yates, Frances A., "Giordano Bruno and the Hermetic Tradition" (1964).

• Twilit Grotto—Esoteric Archives. Giordano Bruno's De Umbris Idearum. Digital edition by Joseph H. Peterson, 1997. (Latin, full text).