MandMaud said:
Most websites and books don't make it plain that they're referring to one or the other kind, at least if you butterfly from page to page as I tend to instead of reading each "introduction", so it's easy to confuse the various systems.
The best approach is to assume that the site is some form of Modern Astrology, unless it explicitly says that it is traditional, or you notice that it doesn't use the outer planets (though it might still be a Vedic site). Most Modern Astrologers don't thing about any form of Astrology before Dane Rudhyar, though that might not stop them using midpoints or hypothetical planets (though there are now far more than enough real ones to go around). They will treat 'classical. Astrology as the works of Leo, Carter, Adams, Ebertin plus a few others.
The trouble is the fairly major breaks in the history of Astrology. The most significant one for our purposes is the break between Lilly and Morin and their immediate followers, at the end of the Seventeenth Centuries and the development of current trends in Astrology, which began with Alan Leo at the end of the nineteenth century but reached it's current dominant interest in jungian psychology in the 1950's.
Even that statement is extremely crude and misleading. The 'break' was more a shift into the background as Astrology ceased to be important to both medicine and to philosophy/science. There are still Astrologers at work but producing little that is significant, with one or two exceptions. With little in the way of formal teaching and legislation that actively penalised Astrologers as fortune tellers. There was little room for development.
Leo was prosecuted in the early twentieth century (1917) for 'fortune telling' and despite attempts to establish Astrology as a 'respectable' system it was not really till the 1950s that really began to blossom with the repeal of the 1735 Witchcraft Act (the last trial was in 1944)
The effect of this legal environment was to force Astrologers to concentrate on 'personality' and 'character' rather than make predictions or forecasts. That is not to say that there was not much valuable work done in the first half of the twentieth century but apart from Leo's 'invention; of a Sun sign approach and the introduction of some vedic beliefs such as the role of the nodes, it was necessarily limited in scope. Certainly in the UK and probably the USA.
Given the predominance of the psychological approach, Astrology is still personality centred today. Again even this is a very crude summary. It ignores other significant developments such as the Hamburg school of the 1930s and the work of Alfred Witte and Rheinold Ebertin, the two most distinguished Astrologers associated with it. Their work led to 'Uranian' Astrology, with its emphasis on hypothetical trans Neptunian planets (and later trans Pluto) and Cosmobiology and its emphasis on mid points. Much of their ideas are incorporated into the work of modern writers who also draw on Jung.
Although ridiculed towards the end of his life for his belief in trans Neptunian planets, Witte's work 'prepared' Astrologers for the discovery of new bodies such as Chiron in 1975 and the raft of bodies discovered since. So we now have a predisposition to treat new planets as having to be of major astrological significance and you will find lots of websites that look at Chiron, Sedna, Eris, Ceres, Haumea, Makemake, either on their own or in combination.
Add to this the development of interest in harmonic 'aspects' and theoretical points then you end up with the possibility of almost unlimited variations of Astrology that are determined by the interests and personality of their inventors. That's why Astrology is a mess at the moment.
Of course not every Astrologer uses everything that is possible but the mix and match approach leads to a lot of individual astrologies, rather than a science of Astrology.
Now that's a very crude summary of events and ideas that really require a book rather than a short post. Disillusion with the new 'Astrology' actually dates back further than you would think, with the questioning of the Tropical Zodiac by such writers as Cyril Fagan. Dave knows a lot more than I ever will on that branch but my point here is that 'events' rather than 'mind' were not lost sight of as the purpose of astrological practice.
The current interest in Traditional practices grew out of a similar disillusionment. At first it was simply aimed at finding out what those practices were, now it's more a process of actually using them. Within the traditional websites, you will probably find that Lilly/Morin sites outnumber the others, because their approach was easiest to access - especially Lilly, who wrote in English.
The Medieval texts are in Latin, either originally or by translation (usuallyfrom Arabic) or Arabic, either originally or by translation ( usually from Farsi (Persian)) That means that someone has to translate them into English or other modern language, or the Astrologer has to learn Latin or even Arabic. Ben Dykes is a literal powerhouse of such translations with others such as Rob Hand and James Holden being heavily involved.
The oldest tradition is Hellenistic (where the use of horoscope charts was invented) and that requires translations from Greek or Latin. Again this makes access more difficult for the modern reader. These too are becoming more accessible.