The Historical Separation of Astrology and Astronomy

In the previous chapters we have seen how astrology passed through various phases of development that first led it from being a sacred and purely hieratic science to becoming a popular, fatalistic and superstitious science. Subsequently we saw how the attention towards the centrality of the individual in humanism favored its philosophical, magical and ascetic development, clearly opposing the divinatory use opposed by a large number of intellectuals led by the disputes of Pico della Mirandola and Savonarola. In this part of our work instead we want to deepen the themes, partly already mentioned, that led what at the time was considered a single science of the stars to divide into two fundamental and essentially independent parts: astronomy and astrology. The separation between these two disciplines must be understood in a very subtle and delicate way to avoid making numerous anachronisms. To avoid misunderstandings it is good to specify that since the early Middle Ages a nominal distinction between astrology and astronomy already existed. Already in Clement of Alexandria we see this first division between astronomy and astrology, which is then taken up by Isidore of Seville and in general, after him by numerous other medieval authors. The need of all these authors was however to distinguish and separate a noble and speculative aspect from a degraded and popular aspect of astrological-astronomical practice. Then however with the passage of time and the development of astronomical practice, naturally these disciplines separated, maintaining however always a close interdependence. In general terms astronomy has always covered a functional role to other disciplines such as astrology, navigation, medicine, agriculture and meteorology without ever having its own autonomous and independent role. Astronomy in fact lacks its own purpose that allows it to emancipate itself and constitute itself as a true and proper science independent from every other discipline. In practice the relationship between astrology and astronomy was a bit like that which could exist between grammar and poetry in a world where there were only alphabets and illiterates: who dedicates themselves to the study of grammar for years without ever writing a poem? Conversely we will see that in this historical period a series of processes occur that lead on one hand to a real collapse of judicial astrology and simultaneously to the separation between an astrology that becomes increasingly philosophical and less divinatory and an astronomy that finds an epistemological foundation for its existence and independence. Let us now try to understand what is the triggering cause that leads to the definitive split between these two disciplines: why do these two disciplines that have always been close to each other separate definitively? In this period great changes happen in astronomy and astrology. Copernicus! Reactions to Copernicus. The Copernican system had many and serious conceptual problems: 1. experimental: from an observational point of view it is the sun that moves around the earth 2. if the earth moved it had to move with respect to the sphere of fixed stars, yet there was no displacement the sphere of fixed stars had to therefore be immense 3. how come if the earth rotates around the sun all things are not dragged towards the west? Copernicanism and Astrology. In reality there was no antithesis between Copernicanism and astrology. Indeed Copernicanism was initially accepted because it responded to a need of mainly astrological character, such as providing a more exact calculation of the position of Mercury and Venus. Something that mainly served astrologers (who else cared about a few degrees of deviation in the position of Mercury or Venus?). From the conceptual point of view there is no contradiction, the greatest heliocentrists were astrologers, as Kepler states the astrologer should not worry about how the position of planets is calculated. It is necessary to give an answer also to the doubt whether it is the sky or the earth that moves? Such doubt does not make Astrology suspicious because it does not concern it. It is in fact sufficient that the astrologer sees how the luminous rays now come from the east then from midday, finally from the west and then disappear [...] For what purpose does the astrologer ask, or rather sublunary nature, how all this happens? In truth it is like for the farmer, who does not ask himself how summer and winter arrive, and yet regulates himself based on them. (Tertius Interveniens, 1610) Of similar opinion is Galileo, who, in a letter to a former student, Monsignor Dini assures the non-conflictuality between the Copernican system and astrological conceptions. However the double approach (Ptolemaic for astrology) and heliocentric for astronomy favored the distinction and separation between the two disciplines. The Experimental Method. It was not even that, the collapse of judicial astrology did not occur due to a collapse caused by a series of failed experiments. For every failed prediction there were as many correct ones. And a fulfilled prediction was worth as much if not more than all the others contradicted. Tycho Brahe and the appearance of new instruments. We will see that it was actually originated by needs of astrological character, also because at the time there was no other reason to see or calculate dots in the sky. That is, for what reason would I ever have been interested in seeing luminous dots in the sky if I had not considered them of some practical or theoretical utility? And at the moment there was no other reason to observe the stars if not the astrological one, then we will see another one appears. Uraniborg. Tycho Brahe was an extremely bizarre and simultaneously charismatic character. Originally from Denmark, more precisely from the castle near the one indicated by Shakespeare for his drama Hamlet, Tycho Brahe had a passion for astrology from childhood which however he was forced to cultivate in secret from his father who wanted to educate him in the humanistic sciences. Decidedly energetic and passionate he lost his nose in a Christmas duel with a young relative Manderup Parsbjerg in 1566 and was forced for the rest of his life to wear a prosthesis composed of gold and silver.