I think what's interesting about the star signs is how they each have a personality associated with them. How old is that idea?
If there are 12 star signs and the idea is old then people had already, prior to MBTI or Jung's ideas, already split people up into 12 personality types.
Gurdjieff's ideas, including enneagram, came from the sufis of the middle east so they were obviously finding patterns within human behaviour and within the human psyche, long ago
The 'four temperaments' is an old idea going back over 2 and a half millenia:
http://en.wikipedia.org/wiki/Table_of_similar_systems_of_comparison_of_temperaments
People were getting to grips with psychology a long time ago and further to that they were exploring the substrata of the human psyche whether by drugs or by meditation, yogic or tantric methods, intuition or perhaps revelation.
The positive side of an understanding of the human mind is the ability to heal. To exercise demons, overcome defence mechanisms, reconcile emotions, learn to listen to the better angel of our judgement.
The dark flip side of an understanding of the human mind is the abuse of such knowledge for example in the exercise of power. The art of kingship and pageantry is largely an exercise in the psychology of dominance....the techniques of which many governments and power elites still use today. The 'father of public relations', Edward Bernays was the nephew of Sigmund Freud and he came to the USA and used Freud's research and ideas about the human mind to manipulate people's emotions through marketing. Advertising and other marketing still uses a lot of psychology today and child psychologists work for large corporations designing marketing campaigns.
For example they have identified that the most vulnerable adults to advertisisng pressure are single mums who hold an underlying guilt which can be exploited. They use what they call the 'nag factor' which is when a child sees a toy on an advert and then goes and nag's their mum for it.
When Jung got his patients to draw the symbols they were seeing in their dreams he found that many of the symbols were found in old hermetic, alchemical texts. Essentially they were archetypal to the human mind.
The power of symbols. Symbols are the language of the subconscious. Medieval paintings and architecture are heavy in symbolism and it seems people were more in touch with this side of things then. Nowadays the meanings of many symbols are lost on many people. They are left with company logos (many of which do have significance) and brands such as the christian cross (solar cross). People are often unable to see the meaning behind things that are right in front of their face (hidden in plain sight).
People have been trained over a period of time to see the world in a specific way...a material / literal way.....a way which is antithetical to the intuitive mind
Here is an image of Madonna, who is famously a Kabbalist:
Kabbalism is about transcending the material plane (malkuth) yet Madonna made a lot of material wealth singing her hit song 'material girl' in which she told women that they shouldn't waste their time with men unless they had money. As far as i'm concerned lady gaga has filled her shoes in flying the flag of materialism and meaningless psuedo-culture
Here is a tshirt from 'rapper' JayZ's clotheswear line, 'Rocawear' (Roca..feller?):
There is a bit of controversy in the UK at the moment because the Iranian Olympic team are threatening to boycott the Olympics, which are being held in London, because they are saying that the Olympic 2012 logo actually spells ZION.....which it clearly does:
I think a lot of people allow themselves to be mislead by meaningless horoscopes in newspapers and magazines which are part of a media which is controlled by a few very powerful people who use the media to shape the way people see the world and to distract people with meaningless shit
That is a dead end. There is far more important and more potent information out there for providing answers both within and without