Magic is something much misunderstood. I define it simply as the transference from imagination to reality: concepts within the ethereal realm of imagination, are brought into physical ('particular') manifestation.
The key idea here is the use of symbols. The ancient cave paintings depicting hunts were created in order to access the immaterial symbolic realm: an 'ideal' prey, the universal deer, is succesfully caught in the imagination, and this is the first step towards making that happen in reality. These works of magical art came about at the point when humanity was realising that we could use our minds independently of our environment. The ability to see with the mind's eye, something which is not real, and furthermore to express this in a form that others can understand. How amazing this must have felt to those first generations who developed these abilities! Now, we take this for granted but we must admit the wondrous power that this must have held for the primitive human beings exploring the new world opening up within them.
Precisely this is why magic has been so important to humans: we are the only animal capable of imagining. As soon as we held this ability, we knew it as a holy process asnd began treating it as such. The direction of imagination through ritual is a potent transformative tool, and essential in reaching individual maturity in a stable manner. It is essential for the ordered cohesion of society. And this, we have been slowly losing our hold on for the past 400 years. Our culture has lost its understanding of - and respect for - the subtle modes of consciousness. Through our bifurcation of reality (ever since Galileo and then Descartes divided Mind from Matter and instructed us that the two may meet but are distinct and separate worlds) and the subsequent hypertrophy of rational intellect (the hard, scientific approach as opposed to the softer, mythical/emotional one) we have reduced all aspects of Mind to an accidental speck, a benign growth from the huge mass of Body.