742 Ulysses Aldrovandi

finally this diagram dissolved into white clouds; while it lasted, the true Sun did not shine clearly.

The poet Virgil mused on similar impressions when he sang:

“The Sun will give you signs; who would dare call the Sun a liar? He even warns that hidden tumults are imminent, and of frauds and secret wars beginning to swell.”

It is worth remembering that in the year following the appearance of the solar diagram described above, the siege and storming of Mantua took place, followed by a terrible plague that occupied all of Cisalpine Gaul—that is, Lombardy.

Furthermore, the circles that sometimes crown the Sun and Moon can vary according to time and place. When a complete circle appears around the Sun, the Moon, or other twinkling stars—whether by night or day, in the morning or the afternoon—it is called an *halos* by the Greeks. Although this word properly signifies a threshing floor in Greek, it is used by Aristotle in his books *On the Heavens* to mean a crown or circle of the stars; in his *Meteorology*, it denotes the complete circle appearing around the Sun and Moon, which is the subject of our present discussion.

An atmospheric halo is formed by internal refraction. Sometimes our vision is refracted and prevented from traveling further because of the air and vapors that have turned into a cloud—specifically a thin cloud with a flat surface. Indeed, when a visual ray travels from a visible object toward the eye of the observer but does not reach it because it is blocked by an obstacle, it is forced to recede, and upon its return, it must spread out. This is perhaps why it creates a round shape; thus, we assert, the halo is formed. Indeed, this crown surrounding the Sun is sometimes observed alongside parhelia (mock suns), as seen in Image II.

Phenomena of this kind have always portended various upheavals in public affairs. For instance, in the year of the world 3823, in Lavinium, between the third and fifth hours, two multicolored circles surrounded the face of the Sun—one showing redness and the other whiteness—and not long after, Carthage was destroyed.

Similarly, in the year of human salvation 851, two circles were observed around the Sun in the city of Paderborn; when they vanished, almost the entire city burned down. Furthermore, in the year of our Lord 1157, a wide circle of fiery and blue color defiled the Sun, and in Normandy, a great abundance of rain followed, which hindered the work of the farmers and produced a high cost of provisions. Likewise, in the year of salvation 1387, a huge circle deformed the Sun in Switzerland; subsequently, famine, wars, and floods brought no small ruin to the inhabitants. Also, in the year 1520, when Charles V, the Holy Roman Emperor, was crowned at Aachen, a "threshing floor" (halo) was seen around the Sun along with a rainbow.

Moreover, Cornelius Gemma claims that on the twenty-ninth of April in the year 1573, from noon until midday, he observed the Sun in an otherwise very clear sky looking remarkably pale and encircled by a ring. Among the more common halos, this one was prodigious: it was as conspicuous as a brilliant rainbow, distinguished by a variety of three colors. Indeed, he adds that the reason for the event could not be relegated to a physical cause alone; rather, as a remarkable image that drew the people's wonder, it was thought to be a portent. Gemma further adds that he had observed many halos where a thin, white, uniform cloud was spread before the face of the Sun in a calm sky. In this case, however, no cloud was visible, yet the circle in the clear sky presented the appearance of a perfect rainbow. From this, he later predicted the hardships of his own times.

However, among other halos, there was a vast and admirable circle around the Sun during the reign of Augustus Caesar, according to Pliny, which appeared like a crown adorned with radiant stars. According to Suetonius and Dio, two other circles surrounded the aforementioned one: one had the form of a most elegant rainbow, while the other was made of wheaten