Liber de consideratione quintae essentiae omnium rerum

This unattributed fifteenth-century manuscript copy of Johannes de Rupecissa's alchemical medical text De consideratione quintae essentiae rerum omnium comprises 52 leaves on parchment, likely the work of more than one scribe.

When compared with the printed Basileae edition (1561), this manuscript has a different (incomplete) preface and lacks the appended works by Arnauldus de Villanova ("De sanguine humano distillato") and Ramon Llull (multiple works). The printed editions held in Special Collections (1561 and 1597) also contain contributions from the editor, Guglielmo Gratarolo. The author of the preface of the manuscript copy is not identified.

The script is a small gothic rotunda by one scribe; each page comprises about 27 lines. An illuminated initial "D" in 5 lines using gold ink and colors (green, red, blue), starts the main text. Other embellishments include later ink foliation, some marginalia, penwork initials, alternating red and blue versals, and paragraph marks.

The volume is bound in a modern cloth binding. Leaves [59-51] contain a fragment of Michele Savonarola's "De aqua vitae."

The item is accompanied by two dealers' descriptions: one in German, the other Italian.