The Cosmic Spheres (Sacrobosco's De sphaera mundi): The Cosmic Spheres consists of nine concentric wheels sourounding the central fixed earth. Below is inscribed: צורת גלגלי שחקים המפורשים באילו פרקים אחד באחד כגלדי בצלים דבוקים (The concentric scheme of the spheres is interpreted as glued onion’s skin), and above with the mnemonic sign for the seven planets' Hebrew names: כל"ש צמח"ן (=כוכב לבנה שבתי צדק מאדים חמה נוגה). The ninth outermost wheel is the mobile circle; the eighth wheel includes the constant small stars and the 12 zodiac signs, while the following seven wheels include the seven constant planets (from outside inwards): Saturn, Jupiter, Mars, Mercury, Venus, Star and Moon, each with its 'servants' (i.e. the correponding zodiac signs); the related elements: earth, water, air, fire (עפר רוח אש מים), and its characteristic climate: cold, warm, wet, dry (קר חם לח יבש). The fixed innermost element, Earth ((ארץ, is surrounded by the other three elements: water (above and below earth, emphasized in black), dry air and fire (מים, אויר יבש, אש).
