Is just a way to make sense of what is happening in the universe by looking at the configurations of the universe itself. Since you can use math to rewind those configurations into the past or fast forward them into the future, astrology also becomes a way to make sense of what happened in the past and what will happen in the future.
In astrology there are 9 planets 12 signs and so on. In the real world there are 94 quintillion zillion gagillion possibilities per minute. So obviously the configuration of the stars, planets, and signs of the universe don’t literally spell out the past, present and future for you. You have to “interpret” the configuration. In other words the configuration is an abstract symbol and if you want concrete details you have to interpret them from the abstract symbol.
There is a very valid reason why the astrological configurations are abstract. It’s because destiny is somewhat abstract. It’s not written in stone that you will get bit by a mosquito 3 cm above your left elbow at 6:38 on March 29th 2013. But it is written in stone that you will feel uncomfortable on your skin around then.
If a person loses a loved one, was that their destiny – or could they have done something to change it? The real thing to understand is that the events of the world, pleasant and unpleasant, are not altogether real in the same way that we instinctively think they are real. There is a reality to them, but it is not what we instinctively percieve as reality. The reality of a situation like losing a loved one is the necessity to experience loss, pain, to increase (or otherwise affect) ones affection for dear people, etc. – in other words, the reality of a situation is more abstract than the concrete details we focus on. So, could we have done something different and avoided the loss of our loved one? Probably not, practically speaking – because such a catastrophic event is very deep and already quite abstract and terribly profound. But even if for argument’s sake we say, “yes, you could have” but the you cannot escape the underlying reality of what is in your destiny – so if you escape one permutation of it taking shape in one way, you only cause it to come at you from a different angle in a different permutation.
The essence of destiny is unavoidable.
Of course this is not fatalism, because destiny is merely a response to our choices of how we use our freewill. So by choosing wisely to be selfless and loving in all ways possible, we create a bright and progressively positive destiny for ourselves. Our future is not out of our control, but our past is. And the present is a mixture.