The first time I encountered the principle of limitation it was in The Cube of Space by Kevin Townley, where he discussed a little known quabalistic glyph and the principle of limitation as it applied to magical work. Recently, in reading R. J. Stewart's The Sphere of Art 2, he also discusses the role of limitation in magic:
Only when we understand how protected, how beneficially limited we are, in our sacromagical work, can we begin to be truly effective. In the classical magical worldview, such wise limitation is often associated with the North, the cosmic Laws of Being the element of Earth. Such limitations associated with Earth require that to take form we must limit force.
It's a point well made that often isn't as appreciated as it could be. Limitation has value as a principle precisely because the movement from potential into reality involves the focus of force into the creation of form. Magic isn't about tossing fireballs or levitating. It's about the focus of force to create measurable results or changes within a person's life, but even change is limited to some degree by the physicality in which it is expressed in.
The realm of ideas is also the realm of endless possibilities or chaos. Nothing is true and everything is permitted, but without limitation all that exists is endless potential. The change from possibility to reality involves some form of limitation. This is why a magical working is really a descriptor and definer of the possibility being brought into reality. In other words, a magical working in and of itself limits the expression of possibility into specific results. The benefit of this is that you achieve a specific result that can be applied to your life, other people's lives etc. The more improbable your possibility, the harder it is to bring into reality, for the simple fact is that it requires more "energy" to overcome the distinct limitations that we deal with on a practical level. At a certain point the exertion of so much "energy" becomes more and more impractical.
Limitation provides an awareness of boundaries, but also provides the magician something to strive for, in terms of bending the rules. While force must be limited in order to manifest form, drawing on force is necessary to create form. Potential doesn't become reality unless force is applied to potential. The realization of form, or the result, is due to the application of force to potential, shaping it, defining it, limiting it, and thus creating form. Force is needed to create form, but the application of force necessarily is a fixation on a specific form or result.
Limitation, in and of itself, is a form of force, in the sense that the limits we encounter actually serve to create possibilities that we can interact with. Sheer potential, which has no limitation, can't really be worked with, until some form of limitation is imposed on it. A blank sheet of paper is raw potential, but once you draw a line, you've limited the potential and started to create the form. The limitation of potential still creates possibilities, but those possibilities are defined by the limitation, and have a relationship with it. The exploration of that relationship is what allows a magician to discover possibilities and begin to move them from potential into reality via magic.
Book Review: The Scientific American Healthy Aging Brain by Judith Horstman
This was a fascinating book to read because of the information it provides on the brain in general, as well as what occurs as your brain ages. The author provided useful advice for keeping your brain sharp as you age and reducing the risks of Alzheimers and Dementia, as well as explaining what types of activity keep the brain stimulated. What I enjoyed the most was how the information was presented without a lot of technical terms or jargon. Anyone could pick this book up and learn a wealth of information about the brain and how it works as well as how aging effects it.