On the Revolutions of the Heavenly Spheres

This single line of manuscript text serves as a translation for a Hebrew inscription found on the title page of this specific copy. In the 16th and 17th centuries, it was common for scholars to write personal religious devotions or biblical verses—often in Hebrew or Greek—on the title pages of their books. This specific phrase is a translation of a vow similar to that of the patriarch Jacob in Genesis 28:21 ("then the Lord shall be my God").